chromecast/base/device_capabilities_impl.cc - chromium/src.git - Git at Google

 // Copyright 2015 The Chromium Authors
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.

 #include "chromecast/base/device_capabilities_impl.h"

 #include <stddef.h>

 #include <utility>

 #include "base/containers/contains.h"
 #include "base/functional/bind.h"
 #include "base/functional/callback_helpers.h"
 #include "base/json/json_writer.h"
 #include "base/logging.h"
 #include "base/memory/ptr_util.h"
 #include "base/not_fatal_until.h"
 #include "base/strings/string_util.h"
 #include "base/task/single_thread_task_runner.h"
 #include "base/values.h"

 namespace chromecast {

 namespace {

 const char kPathSeparator = '.';

 // Determines if a key passed to Register() is valid. No path separators can
 // be present in the key and it must not be empty.
 bool IsValidRegisterKey(const std::string& key) {
   return !key.empty() && !base::Contains(key, kPathSeparator);
 }

 // Determines if a path is valid. This is true if there are no empty keys
 // anywhere in the path (ex: .foo, foo., foo..bar are all invalid).
 bool IsValidPath(const std::string& path) {
   return !path.empty() && *path.begin() != kPathSeparator &&
          *path.rbegin() != kPathSeparator &&
          path.find("..") == std::string::npos;
 }

 // Given a path, gets the first key present in the path (ex: for path "foo.bar"
 // return "foo").
 std::string GetFirstKey(const std::string& path) {
   std::size_t length_to_first_separator = path.find(kPathSeparator);
   return (length_to_first_separator == std::string::npos)
              ? path
              : path.substr(0, length_to_first_separator);
 }

 }  // namespace

 // static Default Capability Keys
 const char DeviceCapabilities::kKeyAssistantSupported[] = "assistant_supported";
 const char DeviceCapabilities::kKeyBluetoothSupported[] = "bluetooth_supported";
 const char DeviceCapabilities::kKeyDisplaySupported[] = "display_supported";
 const char DeviceCapabilities::kKeyHiResAudioSupported[] =
     "hi_res_audio_supported";

 // static
 std::unique_ptr<DeviceCapabilities> DeviceCapabilities::Create() {
   return base::WrapUnique(new DeviceCapabilitiesImpl);
 }

 // static
 std::unique_ptr<DeviceCapabilities> DeviceCapabilities::CreateForTesting() {
   DeviceCapabilities* capabilities = new DeviceCapabilitiesImpl;
   capabilities->SetCapability(kKeyBluetoothSupported, base::Value(false));
   capabilities->SetCapability(kKeyDisplaySupported, base::Value(true));
   capabilities->SetCapability(kKeyHiResAudioSupported, base::Value(false));
   capabilities->SetCapability(kKeyAssistantSupported, base::Value(true));
   return base::WrapUnique(capabilities);
 }

 scoped_refptr<DeviceCapabilities::Data> DeviceCapabilities::CreateData() {
   return base::WrapRefCounted(new Data);
 }

 scoped_refptr<DeviceCapabilities::Data> DeviceCapabilities::CreateData(
     base::Value::Dict dictionary) {
   return base::WrapRefCounted(new Data(std::move(dictionary)));
 }

 DeviceCapabilities::Validator::Validator(DeviceCapabilities* capabilities)
     : capabilities_(capabilities) {
   DCHECK(capabilities);
 }

 void DeviceCapabilities::Validator::SetPublicValidatedValue(
     const std::string& path,
     base::Value new_value) const {
   capabilities_->SetPublicValidatedValue(path, std::move(new_value));
 }

 void DeviceCapabilities::Validator::SetPrivateValidatedValue(
     const std::string& path,
     base::Value new_value) const {
   capabilities_->SetPrivateValidatedValue(path, std::move(new_value));
 }

 DeviceCapabilities::Data::Data() {
   base::JSONWriter::Write(dictionary_, &json_string_);
 }

 DeviceCapabilities::Data::Data(base::Value::Dict dictionary)
     : dictionary_(std::move(dictionary)) {
   base::JSONWriter::Write(dictionary_, &json_string_);
 }

 DeviceCapabilitiesImpl::Data::~Data() {}

 DeviceCapabilitiesImpl::ValidatorInfo::ValidatorInfo(Validator* validator)
     : validator_(validator),
       task_runner_(base::SingleThreadTaskRunner::GetCurrentDefault()) {
   DCHECK(validator_);
   DCHECK(task_runner_.get());
 }

 DeviceCapabilitiesImpl::ValidatorInfo::~ValidatorInfo() {
   // Check that ValidatorInfo is being destroyed on the same thread that it was
   // constructed on.
   DCHECK(task_runner_->BelongsToCurrentThread());
 }

 void DeviceCapabilitiesImpl::ValidatorInfo::Validate(
     const std::string& path,
     base::Value proposed_value) const {
   // Check that we are running Validate on the same thread that ValidatorInfo
   // was constructed on.
   DCHECK(task_runner_->BelongsToCurrentThread());
   validator_->Validate(path, std::move(proposed_value));
 }

 DeviceCapabilitiesImpl::DeviceCapabilitiesImpl()
     : all_data_(CreateData()),
       public_data_(CreateData()),
       task_runner_for_writes_(
           base::SingleThreadTaskRunner::GetCurrentDefault()),
       observer_list_(new base::ObserverListThreadSafe<Observer>) {
   DCHECK(task_runner_for_writes_.get());
 }

 DeviceCapabilitiesImpl::~DeviceCapabilitiesImpl() {
   // Make sure that any registered Validators have unregistered at this point
   DCHECK(validator_map_.empty())
       << "Some validators weren't properly unregistered: " << [this] {
            std::vector<std::string> keys;
            for (const auto& pair : validator_map_) {
              keys.push_back(pair.first);
            }
            return base::JoinString(keys, ", ");
          }();
   // Make sure that all observers have been removed at this point
   observer_list_->AssertEmpty();
 }

 void DeviceCapabilitiesImpl::Register(const std::string& key,
                                       Validator* validator) {
   DCHECK(IsValidRegisterKey(key));
   DCHECK(validator);

   base::AutoLock auto_lock(validation_lock_);
   // Check that a validator has not already been registered for this key
   DCHECK_EQ(0u, validator_map_.count(key));
   validator_map_[key] = std::make_unique<ValidatorInfo>(validator);
 }

 void DeviceCapabilitiesImpl::Unregister(const std::string& key,
                                         const Validator* validator) {
   base::AutoLock auto_lock(validation_lock_);
   auto validator_it = validator_map_.find(key);
   CHECK(validator_it != validator_map_.end(), base::NotFatalUntil::M130);
   // Check that validator being unregistered matches the original for |key|.
   // This prevents managers from accidentally unregistering incorrect
   // validators.
   DCHECK_EQ(validator, validator_it->second->validator());
   // Check that validator is unregistering on same thread that it was
   // registered on
   DCHECK(validator_it->second->task_runner()->BelongsToCurrentThread());
   validator_map_.erase(validator_it);
 }

 DeviceCapabilities::Validator* DeviceCapabilitiesImpl::GetValidator(
     const std::string& key) const {
   base::AutoLock auto_lock(validation_lock_);
   auto validator_it = validator_map_.find(key);
   return validator_it == validator_map_.end()
              ? nullptr
              : validator_it->second->validator();
 }

 bool DeviceCapabilitiesImpl::BluetoothSupported() const {
   scoped_refptr<Data> data_ref = GetAllData();
   auto bluetooth_supported =
       data_ref->dictionary().FindBool(kKeyBluetoothSupported);
   DCHECK(bluetooth_supported);
   return *bluetooth_supported;
 }

 bool DeviceCapabilitiesImpl::DisplaySupported() const {
   scoped_refptr<Data> data_ref = GetAllData();
   auto display_supported =
       data_ref->dictionary().FindBool(kKeyDisplaySupported);
   DCHECK(display_supported);
   return *display_supported;
 }

 bool DeviceCapabilitiesImpl::HiResAudioSupported() const {
   scoped_refptr<Data> data_ref = GetAllData();
   auto hi_res_audio_supported =
       data_ref->dictionary().FindBool(kKeyHiResAudioSupported);
   DCHECK(hi_res_audio_supported);
   return *hi_res_audio_supported;
 }

 bool DeviceCapabilitiesImpl::AssistantSupported() const {
   scoped_refptr<Data> data_ref = GetAllData();
   auto assistant_supported =
       data_ref->dictionary().FindBool(kKeyAssistantSupported);
   DCHECK(assistant_supported);
   return *assistant_supported;
 }

 base::Value DeviceCapabilitiesImpl::GetCapability(
     const std::string& path) const {
   scoped_refptr<Data> data_ref = GetAllData();
   const base::Value* value = data_ref->dictionary().FindByDottedPath(path);
   return value ? value->Clone() : base::Value();
 }

 scoped_refptr<DeviceCapabilities::Data> DeviceCapabilitiesImpl::GetAllData()
     const {
   // Need to acquire lock here when copy constructing all_data_ otherwise we
   // could concurrently be writing to scoped_refptr in SetPublicValidatedValue()
   // or SetPrivateValidatedValue(), which could cause a bad scoped_refptr read.
   base::AutoLock auto_lock(data_lock_);
   return all_data_;
 }

 scoped_refptr<DeviceCapabilities::Data> DeviceCapabilitiesImpl::GetPublicData()
     const {
   // Need to acquire lock here when copy constructing public_data_ otherwise we
   // could concurrently be writing to scoped_refptr in SetPublicValidatedValue()
   // or SetPrivateValidatedValue(), which could cause a bad scoped_refptr read.
   base::AutoLock auto_lock(data_lock_);
   return public_data_;
 }

 void DeviceCapabilitiesImpl::SetCapability(const std::string& path,
                                            base::Value proposed_value) {
   if (!IsValidPath(path)) {
     LOG(DFATAL) << "Invalid capability path encountered for SetCapability()";
     return;
   }

   {
     base::AutoLock auto_lock(validation_lock_);
     // Check for Validator registered under first key per the Register()
     // interface.
     auto validator_it = validator_map_.find(GetFirstKey(path));
     if (validator_it != validator_map_.end()) {
       // We do not want to post a task directly for the Validator's Validate()
       // method here because if another thread is in the middle of unregistering
       // that Validator, there will be an outstanding call to Validate() that
       // occurs after it has unregistered. Since ValidatorInfo gets destroyed
       // in Unregister() on same thread that validation should run on, we can
       // post a task to the Validator's thread with weak_ptr. This way, if the
       // Validator gets unregistered, the call to Validate will get skipped.
       validator_it->second->task_runner()->PostTask(
           FROM_HERE, base::BindOnce(&ValidatorInfo::Validate,
                                     validator_it->second->AsWeakPtr(), path,
                                     std::move(proposed_value)));
       return;
     }
   }
   // Since we are done checking for a registered Validator at this point, we
   // can release the lock. All further member access will be for capabilities.
   // By default, a capability without a validator will be public.
   SetPublicValidatedValue(path, std::move(proposed_value));
 }

 void DeviceCapabilitiesImpl::MergeDictionary(const base::Value::Dict& dict) {
   for (const auto [key, value] : dict) {
     SetCapability(key, value.Clone());
   }
 }

 void DeviceCapabilitiesImpl::AddCapabilitiesObserver(Observer* observer) {
   DCHECK(observer);
   observer_list_->AddObserver(observer);
 }

 void DeviceCapabilitiesImpl::RemoveCapabilitiesObserver(Observer* observer) {
   DCHECK(observer);
   observer_list_->RemoveObserver(observer);
 }

 void DeviceCapabilitiesImpl::SetPublicValidatedValue(const std::string& path,
                                                      base::Value new_value) {
   // All internal writes/modifications of capabilities must occur on same
   // thread to avoid race conditions.
   if (!task_runner_for_writes_->BelongsToCurrentThread()) {
     task_runner_for_writes_->PostTask(
         FROM_HERE,
         base::BindOnce(&DeviceCapabilitiesImpl::SetPublicValidatedValue,
                        base::Unretained(this), path, std::move(new_value)));
     return;
   }

   DCHECK(IsValidPath(path));

   // If the capability exists, it must be public (present in all_data_ and
   // public_data_). We cannot change the privacy of an already existing
   // capability.
   bool is_private = all_data_->dictionary().Find(path) &&
                     !public_data_->dictionary().Find(path);
   if (is_private) {
     NOTREACHED() << "Cannot make a private capability '" << path << "' public.";
   }

   // We don't need to acquire lock here when reading public_data_ because we
   // know that all writes to public_data_ must occur serially on thread that
   // we're on.
   const base::Value* cur_value =
       public_data_->dictionary().FindByDottedPath(path);
   bool capability_unchanged = cur_value && *cur_value == new_value;
   if (capability_unchanged) {
     DVLOG(1) << "Ignoring unchanged public capability: " << path;
     return;
   }

   // In this sequence, we create deep copies for both dictionaries, modify the
   // copies, and then do a pointer swap. We do this to have minimal time spent
   // in the data_lock_. If we were to lock and modify the capabilities
   // dictionary directly, there may be expensive writes that block other
   // threads.
   scoped_refptr<Data> new_public_data = GenerateDataWithNewValue(
       public_data_->dictionary(), path, new_value.Clone());
   scoped_refptr<Data> new_data = GenerateDataWithNewValue(
       all_data_->dictionary(), path, std::move(new_value));

   {
     base::AutoLock auto_lock(data_lock_);
     // Using swap instead of assignment operator here because it's a little
     // faster. Avoids an extra call to AddRef()/Release().
     public_data_.swap(new_public_data);
     all_data_.swap(new_data);
   }

   // Even though ObserverListThreadSafe notifications are always asynchronous
   // (posts task even if to same thread), no locks should be held at this point
   // in the code. This is just to be safe that no deadlocks occur if Observers
   // call DeviceCapabilities methods in OnCapabilitiesChanged().
   observer_list_->Notify(FROM_HERE, &Observer::OnCapabilitiesChanged, path);
 }

 void DeviceCapabilitiesImpl::SetPrivateValidatedValue(const std::string& path,
                                                       base::Value new_value) {
   // All internal writes/modifications of capabilities must occur on same
   // thread to avoid race conditions.
   if (!task_runner_for_writes_->BelongsToCurrentThread()) {
     task_runner_for_writes_->PostTask(
         FROM_HERE,
         base::BindOnce(&DeviceCapabilitiesImpl::SetPrivateValidatedValue,
                        base::Unretained(this), path, std::move(new_value)));
     return;
   }

   DCHECK(IsValidPath(path));

   // If the capability exists, it must be private (present in all_data_ only).
   // We cannot change the privacy of an already existing capability.
   const auto* is_public = public_data_->dictionary().Find(path);
   if (is_public) {
     NOTREACHED() << "Cannot make a public capability '" << path << "' private.";
   }

   // We don't need to acquire lock here when reading all_data_ because we know
   // that all writes to all_data_ must occur serially on thread that we're on.
   const base::Value* cur_value = all_data_->dictionary().FindByDottedPath(path);
   bool capability_unchanged = cur_value && *cur_value == new_value;
   if (capability_unchanged) {
     DVLOG(1) << "Ignoring unchanged capability: " << path;
     return;
   }

   // In this sequence, we create a deep copy, modify the deep copy, and then
   // do a pointer swap. We do this to have minimal time spent in the
   // data_lock_. If we were to lock and modify the capabilities
   // dictionary directly, there may be expensive writes that block other
   // threads.
   scoped_refptr<Data> new_data = GenerateDataWithNewValue(
       all_data_->dictionary(), path, std::move(new_value));

   {
     base::AutoLock auto_lock(data_lock_);
     // Using swap instead of assignment operator here because it's a little
     // faster. Avoids an extra call to AddRef()/Release().
     all_data_.swap(new_data);
   }

   // Even though ObserverListThreadSafe notifications are always asynchronous
   // (posts task even if to same thread), no locks should be held at this point
   // in the code. This is just to be safe that no deadlocks occur if Observers
   // call DeviceCapabilities methods in OnCapabilitiesChanged().
   observer_list_->Notify(FROM_HERE, &Observer::OnCapabilitiesChanged, path);
 }

 scoped_refptr<DeviceCapabilities::Data>
 DeviceCapabilitiesImpl::GenerateDataWithNewValue(const base::Value::Dict& dict,
                                                  const std::string& path,
                                                  base::Value new_value) {
   base::Value::Dict dict_deep_copy(dict.Clone());
   dict_deep_copy.SetByDottedPath(path, std::move(new_value));
   return CreateData(std::move(dict_deep_copy));
 }

 }  // namespace chromecast
	// Copyright 2015 The Chromium Authors
	// Use of this source code is governed by a BSD-style license that can be
	// found in the LICENSE file.

	#include "chromecast/base/device_capabilities_impl.h"

	#include <stddef.h>

	#include <utility>

	#include "base/containers/contains.h"
	#include "base/functional/bind.h"
	#include "base/functional/callback_helpers.h"
	#include "base/json/json_writer.h"
	#include "base/logging.h"
	#include "base/memory/ptr_util.h"
	#include "base/not_fatal_until.h"
	#include "base/strings/string_util.h"
	#include "base/task/single_thread_task_runner.h"
	#include "base/values.h"

	namespace chromecast {

	namespace {

	const char kPathSeparator = '.';

	// Determines if a key passed to Register() is valid. No path separators can
	// be present in the key and it must not be empty.
	bool IsValidRegisterKey(const std::string& key) {
	return !key.empty() && !base::Contains(key, kPathSeparator);
	}

	// Determines if a path is valid. This is true if there are no empty keys
	// anywhere in the path (ex: .foo, foo., foo..bar are all invalid).
	bool IsValidPath(const std::string& path) {
	return !path.empty() && *path.begin() != kPathSeparator &&
	*path.rbegin() != kPathSeparator &&
	path.find("..") == std::string::npos;
	}

	// Given a path, gets the first key present in the path (ex: for path "foo.bar"
	// return "foo").
	std::string GetFirstKey(const std::string& path) {
	std::size_t length_to_first_separator = path.find(kPathSeparator);
	return (length_to_first_separator == std::string::npos)
	? path
	: path.substr(0, length_to_first_separator);
	}

	} // namespace

	// static Default Capability Keys
	const char DeviceCapabilities::kKeyAssistantSupported[] = "assistant_supported";
	const char DeviceCapabilities::kKeyBluetoothSupported[] = "bluetooth_supported";
	const char DeviceCapabilities::kKeyDisplaySupported[] = "display_supported";
	const char DeviceCapabilities::kKeyHiResAudioSupported[] =
	"hi_res_audio_supported";

	// static
	std::unique_ptr<DeviceCapabilities> DeviceCapabilities::Create() {
	return base::WrapUnique(new DeviceCapabilitiesImpl);
	}

	// static
	std::unique_ptr<DeviceCapabilities> DeviceCapabilities::CreateForTesting() {
	DeviceCapabilities* capabilities = new DeviceCapabilitiesImpl;
	capabilities->SetCapability(kKeyBluetoothSupported, base::Value(false));
	capabilities->SetCapability(kKeyDisplaySupported, base::Value(true));
	capabilities->SetCapability(kKeyHiResAudioSupported, base::Value(false));
	capabilities->SetCapability(kKeyAssistantSupported, base::Value(true));
	return base::WrapUnique(capabilities);
	}

	scoped_refptr<DeviceCapabilities::Data> DeviceCapabilities::CreateData() {
	return base::WrapRefCounted(new Data);
	}

	scoped_refptr<DeviceCapabilities::Data> DeviceCapabilities::CreateData(
	base::Value::Dict dictionary) {
	return base::WrapRefCounted(new Data(std::move(dictionary)));
	}

	DeviceCapabilities::Validator::Validator(DeviceCapabilities* capabilities)
	: capabilities_(capabilities) {
	DCHECK(capabilities);
	}

	void DeviceCapabilities::Validator::SetPublicValidatedValue(
	const std::string& path,
	base::Value new_value) const {
	capabilities_->SetPublicValidatedValue(path, std::move(new_value));
	}

	void DeviceCapabilities::Validator::SetPrivateValidatedValue(
	const std::string& path,
	base::Value new_value) const {
	capabilities_->SetPrivateValidatedValue(path, std::move(new_value));
	}

	DeviceCapabilities::Data::Data() {
	base::JSONWriter::Write(dictionary_, &json_string_);
	}

	DeviceCapabilities::Data::Data(base::Value::Dict dictionary)
	: dictionary_(std::move(dictionary)) {
	base::JSONWriter::Write(dictionary_, &json_string_);
	}

	DeviceCapabilitiesImpl::Data::~Data() {}

	DeviceCapabilitiesImpl::ValidatorInfo::ValidatorInfo(Validator* validator)
	: validator_(validator),
	task_runner_(base::SingleThreadTaskRunner::GetCurrentDefault()) {
	DCHECK(validator_);
	DCHECK(task_runner_.get());
	}

	DeviceCapabilitiesImpl::ValidatorInfo::~ValidatorInfo() {
	// Check that ValidatorInfo is being destroyed on the same thread that it was
	// constructed on.
	DCHECK(task_runner_->BelongsToCurrentThread());
	}

	void DeviceCapabilitiesImpl::ValidatorInfo::Validate(
	const std::string& path,
	base::Value proposed_value) const {
	// Check that we are running Validate on the same thread that ValidatorInfo
	// was constructed on.
	DCHECK(task_runner_->BelongsToCurrentThread());
	validator_->Validate(path, std::move(proposed_value));
	}

	DeviceCapabilitiesImpl::DeviceCapabilitiesImpl()
	: all_data_(CreateData()),
	public_data_(CreateData()),
	task_runner_for_writes_(
	base::SingleThreadTaskRunner::GetCurrentDefault()),
	observer_list_(new base::ObserverListThreadSafe<Observer>) {
	DCHECK(task_runner_for_writes_.get());
	}

	DeviceCapabilitiesImpl::~DeviceCapabilitiesImpl() {
	// Make sure that any registered Validators have unregistered at this point
	DCHECK(validator_map_.empty())
	<< "Some validators weren't properly unregistered: " << [this] {
	std::vector<std::string> keys;
	for (const auto& pair : validator_map_) {
	keys.push_back(pair.first);
	}
	return base::JoinString(keys, ", ");
	}();
	// Make sure that all observers have been removed at this point
	observer_list_->AssertEmpty();
	}

	void DeviceCapabilitiesImpl::Register(const std::string& key,
	Validator* validator) {
	DCHECK(IsValidRegisterKey(key));
	DCHECK(validator);

	base::AutoLock auto_lock(validation_lock_);
	// Check that a validator has not already been registered for this key
	DCHECK_EQ(0u, validator_map_.count(key));
	validator_map_[key] = std::make_unique<ValidatorInfo>(validator);
	}

	void DeviceCapabilitiesImpl::Unregister(const std::string& key,
	const Validator* validator) {
	base::AutoLock auto_lock(validation_lock_);
	auto validator_it = validator_map_.find(key);
	CHECK(validator_it != validator_map_.end(), base::NotFatalUntil::M130);
	// Check that validator being unregistered matches the original for \|key\|.
	// This prevents managers from accidentally unregistering incorrect
	// validators.
	DCHECK_EQ(validator, validator_it->second->validator());
	// Check that validator is unregistering on same thread that it was
	// registered on
	DCHECK(validator_it->second->task_runner()->BelongsToCurrentThread());
	validator_map_.erase(validator_it);
	}

	DeviceCapabilities::Validator* DeviceCapabilitiesImpl::GetValidator(
	const std::string& key) const {
	base::AutoLock auto_lock(validation_lock_);
	auto validator_it = validator_map_.find(key);
	return validator_it == validator_map_.end()
	? nullptr
	: validator_it->second->validator();
	}

	bool DeviceCapabilitiesImpl::BluetoothSupported() const {
	scoped_refptr<Data> data_ref = GetAllData();
	auto bluetooth_supported =
	data_ref->dictionary().FindBool(kKeyBluetoothSupported);
	DCHECK(bluetooth_supported);
	return *bluetooth_supported;
	}

	bool DeviceCapabilitiesImpl::DisplaySupported() const {
	scoped_refptr<Data> data_ref = GetAllData();
	auto display_supported =
	data_ref->dictionary().FindBool(kKeyDisplaySupported);
	DCHECK(display_supported);
	return *display_supported;
	}

	bool DeviceCapabilitiesImpl::HiResAudioSupported() const {
	scoped_refptr<Data> data_ref = GetAllData();
	auto hi_res_audio_supported =
	data_ref->dictionary().FindBool(kKeyHiResAudioSupported);
	DCHECK(hi_res_audio_supported);
	return *hi_res_audio_supported;
	}

	bool DeviceCapabilitiesImpl::AssistantSupported() const {
	scoped_refptr<Data> data_ref = GetAllData();
	auto assistant_supported =
	data_ref->dictionary().FindBool(kKeyAssistantSupported);
	DCHECK(assistant_supported);
	return *assistant_supported;
	}

	base::Value DeviceCapabilitiesImpl::GetCapability(
	const std::string& path) const {
	scoped_refptr<Data> data_ref = GetAllData();
	const base::Value* value = data_ref->dictionary().FindByDottedPath(path);
	return value ? value->Clone() : base::Value();
	}

	scoped_refptr<DeviceCapabilities::Data> DeviceCapabilitiesImpl::GetAllData()
	const {
	// Need to acquire lock here when copy constructing all_data_ otherwise we
	// could concurrently be writing to scoped_refptr in SetPublicValidatedValue()
	// or SetPrivateValidatedValue(), which could cause a bad scoped_refptr read.
	base::AutoLock auto_lock(data_lock_);
	return all_data_;
	}

	scoped_refptr<DeviceCapabilities::Data> DeviceCapabilitiesImpl::GetPublicData()
	const {
	// Need to acquire lock here when copy constructing public_data_ otherwise we
	// could concurrently be writing to scoped_refptr in SetPublicValidatedValue()
	// or SetPrivateValidatedValue(), which could cause a bad scoped_refptr read.
	base::AutoLock auto_lock(data_lock_);
	return public_data_;
	}

	void DeviceCapabilitiesImpl::SetCapability(const std::string& path,
	base::Value proposed_value) {
	if (!IsValidPath(path)) {
	LOG(DFATAL) << "Invalid capability path encountered for SetCapability()";
	return;
	}

	{
	base::AutoLock auto_lock(validation_lock_);
	// Check for Validator registered under first key per the Register()
	// interface.
	auto validator_it = validator_map_.find(GetFirstKey(path));
	if (validator_it != validator_map_.end()) {
	// We do not want to post a task directly for the Validator's Validate()
	// method here because if another thread is in the middle of unregistering
	// that Validator, there will be an outstanding call to Validate() that
	// occurs after it has unregistered. Since ValidatorInfo gets destroyed
	// in Unregister() on same thread that validation should run on, we can
	// post a task to the Validator's thread with weak_ptr. This way, if the
	// Validator gets unregistered, the call to Validate will get skipped.
	validator_it->second->task_runner()->PostTask(
	FROM_HERE, base::BindOnce(&ValidatorInfo::Validate,
	validator_it->second->AsWeakPtr(), path,
	std::move(proposed_value)));
	return;
	}
	}
	// Since we are done checking for a registered Validator at this point, we
	// can release the lock. All further member access will be for capabilities.
	// By default, a capability without a validator will be public.
	SetPublicValidatedValue(path, std::move(proposed_value));
	}

	void DeviceCapabilitiesImpl::MergeDictionary(const base::Value::Dict& dict) {
	for (const auto [key, value] : dict) {
	SetCapability(key, value.Clone());
	}
	}

	void DeviceCapabilitiesImpl::AddCapabilitiesObserver(Observer* observer) {
	DCHECK(observer);
	observer_list_->AddObserver(observer);
	}

	void DeviceCapabilitiesImpl::RemoveCapabilitiesObserver(Observer* observer) {
	DCHECK(observer);
	observer_list_->RemoveObserver(observer);
	}

	void DeviceCapabilitiesImpl::SetPublicValidatedValue(const std::string& path,
	base::Value new_value) {
	// All internal writes/modifications of capabilities must occur on same
	// thread to avoid race conditions.
	if (!task_runner_for_writes_->BelongsToCurrentThread()) {
	task_runner_for_writes_->PostTask(
	FROM_HERE,
	base::BindOnce(&DeviceCapabilitiesImpl::SetPublicValidatedValue,
	base::Unretained(this), path, std::move(new_value)));
	return;
	}

	DCHECK(IsValidPath(path));

	// If the capability exists, it must be public (present in all_data_ and
	// public_data_). We cannot change the privacy of an already existing
	// capability.
	bool is_private = all_data_->dictionary().Find(path) &&
	!public_data_->dictionary().Find(path);
	if (is_private) {
	NOTREACHED() << "Cannot make a private capability '" << path << "' public.";
	}

	// We don't need to acquire lock here when reading public_data_ because we
	// know that all writes to public_data_ must occur serially on thread that
	// we're on.
	const base::Value* cur_value =
	public_data_->dictionary().FindByDottedPath(path);
	bool capability_unchanged = cur_value && *cur_value == new_value;
	if (capability_unchanged) {
	DVLOG(1) << "Ignoring unchanged public capability: " << path;
	return;
	}

	// In this sequence, we create deep copies for both dictionaries, modify the
	// copies, and then do a pointer swap. We do this to have minimal time spent
	// in the data_lock_. If we were to lock and modify the capabilities
	// dictionary directly, there may be expensive writes that block other
	// threads.
	scoped_refptr<Data> new_public_data = GenerateDataWithNewValue(
	public_data_->dictionary(), path, new_value.Clone());
	scoped_refptr<Data> new_data = GenerateDataWithNewValue(
	all_data_->dictionary(), path, std::move(new_value));

	{
	base::AutoLock auto_lock(data_lock_);
	// Using swap instead of assignment operator here because it's a little
	// faster. Avoids an extra call to AddRef()/Release().
	public_data_.swap(new_public_data);
	all_data_.swap(new_data);
	}

	// Even though ObserverListThreadSafe notifications are always asynchronous
	// (posts task even if to same thread), no locks should be held at this point
	// in the code. This is just to be safe that no deadlocks occur if Observers
	// call DeviceCapabilities methods in OnCapabilitiesChanged().
	observer_list_->Notify(FROM_HERE, &Observer::OnCapabilitiesChanged, path);
	}

	void DeviceCapabilitiesImpl::SetPrivateValidatedValue(const std::string& path,
	base::Value new_value) {
	// All internal writes/modifications of capabilities must occur on same
	// thread to avoid race conditions.
	if (!task_runner_for_writes_->BelongsToCurrentThread()) {
	task_runner_for_writes_->PostTask(
	FROM_HERE,
	base::BindOnce(&DeviceCapabilitiesImpl::SetPrivateValidatedValue,
	base::Unretained(this), path, std::move(new_value)));
	return;
	}

	DCHECK(IsValidPath(path));

	// If the capability exists, it must be private (present in all_data_ only).
	// We cannot change the privacy of an already existing capability.
	const auto* is_public = public_data_->dictionary().Find(path);
	if (is_public) {
	NOTREACHED() << "Cannot make a public capability '" << path << "' private.";
	}

	// We don't need to acquire lock here when reading all_data_ because we know
	// that all writes to all_data_ must occur serially on thread that we're on.
	const base::Value* cur_value = all_data_->dictionary().FindByDottedPath(path);
	bool capability_unchanged = cur_value && *cur_value == new_value;
	if (capability_unchanged) {
	DVLOG(1) << "Ignoring unchanged capability: " << path;
	return;
	}

	// In this sequence, we create a deep copy, modify the deep copy, and then
	// do a pointer swap. We do this to have minimal time spent in the
	// data_lock_. If we were to lock and modify the capabilities
	// dictionary directly, there may be expensive writes that block other
	// threads.
	scoped_refptr<Data> new_data = GenerateDataWithNewValue(
	all_data_->dictionary(), path, std::move(new_value));

	{
	base::AutoLock auto_lock(data_lock_);
	// Using swap instead of assignment operator here because it's a little
	// faster. Avoids an extra call to AddRef()/Release().
	all_data_.swap(new_data);
	}

	// Even though ObserverListThreadSafe notifications are always asynchronous
	// (posts task even if to same thread), no locks should be held at this point
	// in the code. This is just to be safe that no deadlocks occur if Observers
	// call DeviceCapabilities methods in OnCapabilitiesChanged().
	observer_list_->Notify(FROM_HERE, &Observer::OnCapabilitiesChanged, path);
	}

	scoped_refptr<DeviceCapabilities::Data>
	DeviceCapabilitiesImpl::GenerateDataWithNewValue(const base::Value::Dict& dict,
	const std::string& path,
	base::Value new_value) {
	base::Value::Dict dict_deep_copy(dict.Clone());
	dict_deep_copy.SetByDottedPath(path, std::move(new_value));
	return CreateData(std::move(dict_deep_copy));
	}

	} // namespace chromecast