content/child/child_discardable_shared_memory_manager.cc - chromium/src - Git at Google

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.

 #include "content/child/child_discardable_shared_memory_manager.h"

 #include <algorithm>
 #include <utility>

 #include "base/atomic_sequence_num.h"
 #include "base/bind.h"
 #include "base/debug/crash_logging.h"
 #include "base/macros.h"
 #include "base/memory/discardable_memory.h"
 #include "base/memory/discardable_shared_memory.h"
 #include "base/memory/ptr_util.h"
 #include "base/metrics/histogram.h"
 #include "base/process/memory.h"
 #include "base/process/process_metrics.h"
 #include "base/strings/string_number_conversions.h"
 #include "base/thread_task_runner_handle.h"
 #include "base/trace_event/memory_dump_manager.h"
 #include "base/trace_event/trace_event.h"
 #include "content/common/child_process_messages.h"

 namespace content {
 namespace {

 // Default allocation size.
 const size_t kAllocationSize = 4 * 1024 * 1024;

 // Global atomic to generate unique discardable shared memory IDs.
 base::StaticAtomicSequenceNumber g_next_discardable_shared_memory_id;

 class DiscardableMemoryImpl : public base::DiscardableMemory {
  public:
   DiscardableMemoryImpl(ChildDiscardableSharedMemoryManager* manager,
                         std::unique_ptr<DiscardableSharedMemoryHeap::Span> span)
       : manager_(manager), span_(std::move(span)), is_locked_(true) {}

   ~DiscardableMemoryImpl() override {
     if (is_locked_)
       manager_->UnlockSpan(span_.get());

     manager_->ReleaseSpan(std::move(span_));
   }

   // Overridden from base::DiscardableMemory:
   bool Lock() override {
     DCHECK(!is_locked_);

     if (!manager_->LockSpan(span_.get()))
       return false;

     is_locked_ = true;
     return true;
   }
   void Unlock() override {
     DCHECK(is_locked_);

     manager_->UnlockSpan(span_.get());
     is_locked_ = false;
   }
   void* data() const override {
     DCHECK(is_locked_);
     return reinterpret_cast<void*>(span_->start() * base::GetPageSize());
   }

   base::trace_event::MemoryAllocatorDump* CreateMemoryAllocatorDump(
       const char* name,
       base::trace_event::ProcessMemoryDump* pmd) const override {
     return manager_->CreateMemoryAllocatorDump(span_.get(), name, pmd);
   }

  private:
   ChildDiscardableSharedMemoryManager* const manager_;
   std::unique_ptr<DiscardableSharedMemoryHeap::Span> span_;
   bool is_locked_;

   DISALLOW_COPY_AND_ASSIGN(DiscardableMemoryImpl);
 };

 void SendDeletedDiscardableSharedMemoryMessage(
     scoped_refptr<ThreadSafeSender> sender,
     DiscardableSharedMemoryId id) {
   sender->Send(new ChildProcessHostMsg_DeletedDiscardableSharedMemory(id));
 }

 }  // namespace

 ChildDiscardableSharedMemoryManager::ChildDiscardableSharedMemoryManager(
     ThreadSafeSender* sender)
     : heap_(base::GetPageSize()), sender_(sender) {
   base::trace_event::MemoryDumpManager::GetInstance()->RegisterDumpProvider(
       this, "ChildDiscardableSharedMemoryManager",
       base::ThreadTaskRunnerHandle::Get());
 }

 ChildDiscardableSharedMemoryManager::~ChildDiscardableSharedMemoryManager() {
   base::trace_event::MemoryDumpManager::GetInstance()->UnregisterDumpProvider(
       this);
   // TODO(reveman): Determine if this DCHECK can be enabled. crbug.com/430533
   // DCHECK_EQ(heap_.GetSize(), heap_.GetSizeOfFreeLists());
   if (heap_.GetSize())
     MemoryUsageChanged(0, 0);
 }

 std::unique_ptr<base::DiscardableMemory>
 ChildDiscardableSharedMemoryManager::AllocateLockedDiscardableMemory(
     size_t size) {
   base::AutoLock lock(lock_);

   // TODO(reveman): Temporary diagnostics for http://crbug.com/577786.
   CHECK_NE(size, 0u);

   UMA_HISTOGRAM_CUSTOM_COUNTS("Memory.DiscardableAllocationSize",
                               size / 1024,  // In KB
                               1,
                               4 * 1024 * 1024,  // 4 GB
                               50);

   // Round up to multiple of page size.
   size_t pages =
       std::max((size + base::GetPageSize() - 1) / base::GetPageSize(),
                static_cast<size_t>(1));

   // Default allocation size in pages.
   size_t allocation_pages = kAllocationSize / base::GetPageSize();

   size_t slack = 0;
   // When searching the free lists, allow a slack between required size and
   // free span size that is less or equal to kAllocationSize. This is to
   // avoid segments larger then kAllocationSize unless they are a perfect
   // fit. The result is that large allocations can be reused without reducing
   // the ability to discard memory.
   if (pages < allocation_pages)
     slack = allocation_pages - pages;

   size_t heap_size_prior_to_releasing_purged_memory = heap_.GetSize();
   for (;;) {
     // Search free lists for suitable span.
     std::unique_ptr<DiscardableSharedMemoryHeap::Span> free_span =
         heap_.SearchFreeLists(pages, slack);
     if (!free_span.get())
       break;

     // Attempt to lock |free_span|. Delete span and search free lists again
     // if locking failed.
     if (free_span->shared_memory()->Lock(
             free_span->start() * base::GetPageSize() -
                 reinterpret_cast<size_t>(free_span->shared_memory()->memory()),
             free_span->length() * base::GetPageSize()) ==
         base::DiscardableSharedMemory::FAILED) {
       DCHECK(!free_span->shared_memory()->IsMemoryResident());
       // We have to release purged memory before |free_span| can be destroyed.
       heap_.ReleasePurgedMemory();
       DCHECK(!free_span->shared_memory());
       continue;
     }

     free_span->set_is_locked(true);

     // Memory usage is guaranteed to have changed after having removed
     // at least one span from the free lists.
     MemoryUsageChanged(heap_.GetSize(), heap_.GetSizeOfFreeLists());

     return base::WrapUnique(
         new DiscardableMemoryImpl(this, std::move(free_span)));
   }

   // Release purged memory to free up the address space before we attempt to
   // allocate more memory.
   heap_.ReleasePurgedMemory();

   // Make sure crash keys are up to date in case allocation fails.
   if (heap_.GetSize() != heap_size_prior_to_releasing_purged_memory)
     MemoryUsageChanged(heap_.GetSize(), heap_.GetSizeOfFreeLists());

   size_t pages_to_allocate =
       std::max(kAllocationSize / base::GetPageSize(), pages);
   size_t allocation_size_in_bytes = pages_to_allocate * base::GetPageSize();

   DiscardableSharedMemoryId new_id =
       g_next_discardable_shared_memory_id.GetNext();

   // Ask parent process to allocate a new discardable shared memory segment.
   std::unique_ptr<base::DiscardableSharedMemory> shared_memory(
       AllocateLockedDiscardableSharedMemory(allocation_size_in_bytes, new_id));

   // Create span for allocated memory.
   std::unique_ptr<DiscardableSharedMemoryHeap::Span> new_span(heap_.Grow(
       std::move(shared_memory), allocation_size_in_bytes, new_id,
       base::Bind(&SendDeletedDiscardableSharedMemoryMessage, sender_, new_id)));
   new_span->set_is_locked(true);

   // Unlock and insert any left over memory into free lists.
   if (pages < pages_to_allocate) {
     std::unique_ptr<DiscardableSharedMemoryHeap::Span> leftover =
         heap_.Split(new_span.get(), pages);
     leftover->shared_memory()->Unlock(
         leftover->start() * base::GetPageSize() -
             reinterpret_cast<size_t>(leftover->shared_memory()->memory()),
         leftover->length() * base::GetPageSize());
     leftover->set_is_locked(false);
     heap_.MergeIntoFreeLists(std::move(leftover));
   }

   MemoryUsageChanged(heap_.GetSize(), heap_.GetSizeOfFreeLists());

   return base::WrapUnique(new DiscardableMemoryImpl(this, std::move(new_span)));
 }

 bool ChildDiscardableSharedMemoryManager::OnMemoryDump(
     const base::trace_event::MemoryDumpArgs& args,
     base::trace_event::ProcessMemoryDump* pmd) {
   base::AutoLock lock(lock_);
   return heap_.OnMemoryDump(pmd);
 }

 void ChildDiscardableSharedMemoryManager::ReleaseFreeMemory() {
   base::AutoLock lock(lock_);

   size_t heap_size_prior_to_releasing_memory = heap_.GetSize();

   // Release both purged and free memory.
   heap_.ReleasePurgedMemory();
   heap_.ReleaseFreeMemory();

   if (heap_.GetSize() != heap_size_prior_to_releasing_memory)
     MemoryUsageChanged(heap_.GetSize(), heap_.GetSizeOfFreeLists());
 }

 bool ChildDiscardableSharedMemoryManager::LockSpan(
     DiscardableSharedMemoryHeap::Span* span) {
   base::AutoLock lock(lock_);

   if (!span->shared_memory())
     return false;

   size_t offset = span->start() * base::GetPageSize() -
       reinterpret_cast<size_t>(span->shared_memory()->memory());
   size_t length = span->length() * base::GetPageSize();

   switch (span->shared_memory()->Lock(offset, length)) {
     case base::DiscardableSharedMemory::SUCCESS:
       span->set_is_locked(true);
       return true;
     case base::DiscardableSharedMemory::PURGED:
       span->shared_memory()->Unlock(offset, length);
       span->set_is_locked(false);
       return false;
     case base::DiscardableSharedMemory::FAILED:
       return false;
   }

   NOTREACHED();
   return false;
 }

 void ChildDiscardableSharedMemoryManager::UnlockSpan(
     DiscardableSharedMemoryHeap::Span* span) {
   base::AutoLock lock(lock_);

   DCHECK(span->shared_memory());
   size_t offset = span->start() * base::GetPageSize() -
       reinterpret_cast<size_t>(span->shared_memory()->memory());
   size_t length = span->length() * base::GetPageSize();

   span->set_is_locked(false);
   return span->shared_memory()->Unlock(offset, length);
 }

 void ChildDiscardableSharedMemoryManager::ReleaseSpan(
     std::unique_ptr<DiscardableSharedMemoryHeap::Span> span) {
   base::AutoLock lock(lock_);

   // Delete span instead of merging it into free lists if memory is gone.
   if (!span->shared_memory())
     return;

   heap_.MergeIntoFreeLists(std::move(span));

   // Bytes of free memory changed.
   MemoryUsageChanged(heap_.GetSize(), heap_.GetSizeOfFreeLists());
 }

 base::trace_event::MemoryAllocatorDump*
 ChildDiscardableSharedMemoryManager::CreateMemoryAllocatorDump(
     DiscardableSharedMemoryHeap::Span* span,
     const char* name,
     base::trace_event::ProcessMemoryDump* pmd) const {
   base::AutoLock lock(lock_);
   return heap_.CreateMemoryAllocatorDump(span, name, pmd);
 }

 std::unique_ptr<base::DiscardableSharedMemory>
 ChildDiscardableSharedMemoryManager::AllocateLockedDiscardableSharedMemory(
     size_t size,
     DiscardableSharedMemoryId id) {
   TRACE_EVENT2("renderer",
                "ChildDiscardableSharedMemoryManager::"
                "AllocateLockedDiscardableSharedMemory",
                "size", size, "id", id);

   base::SharedMemoryHandle handle = base::SharedMemory::NULLHandle();
   sender_->Send(
       new ChildProcessHostMsg_SyncAllocateLockedDiscardableSharedMemory(
           size, id, &handle));
   std::unique_ptr<base::DiscardableSharedMemory> memory(
       new base::DiscardableSharedMemory(handle));
   if (!memory->Map(size))
     base::TerminateBecauseOutOfMemory(size);
   return memory;
 }

 void ChildDiscardableSharedMemoryManager::MemoryUsageChanged(
     size_t new_bytes_total,
     size_t new_bytes_free) const {
   static const char kDiscardableMemoryAllocatedKey[] =
       "discardable-memory-allocated";
   base::debug::SetCrashKeyValue(kDiscardableMemoryAllocatedKey,
                                 base::Uint64ToString(new_bytes_total));

   static const char kDiscardableMemoryFreeKey[] = "discardable-memory-free";
   base::debug::SetCrashKeyValue(kDiscardableMemoryFreeKey,
                                 base::Uint64ToString(new_bytes_free));
 }

 }  // namespace content
	// Copyright 2014 The Chromium Authors. All rights reserved.
	// Use of this source code is governed by a BSD-style license that can be
	// found in the LICENSE file.

	#include "content/child/child_discardable_shared_memory_manager.h"

	#include <algorithm>
	#include <utility>

	#include "base/atomic_sequence_num.h"
	#include "base/bind.h"
	#include "base/debug/crash_logging.h"
	#include "base/macros.h"
	#include "base/memory/discardable_memory.h"
	#include "base/memory/discardable_shared_memory.h"
	#include "base/memory/ptr_util.h"
	#include "base/metrics/histogram.h"
	#include "base/process/memory.h"
	#include "base/process/process_metrics.h"
	#include "base/strings/string_number_conversions.h"
	#include "base/thread_task_runner_handle.h"
	#include "base/trace_event/memory_dump_manager.h"
	#include "base/trace_event/trace_event.h"
	#include "content/common/child_process_messages.h"

	namespace content {
	namespace {

	// Default allocation size.
	const size_t kAllocationSize = 4 * 1024 * 1024;

	// Global atomic to generate unique discardable shared memory IDs.
	base::StaticAtomicSequenceNumber g_next_discardable_shared_memory_id;

	class DiscardableMemoryImpl : public base::DiscardableMemory {
	public:
	DiscardableMemoryImpl(ChildDiscardableSharedMemoryManager* manager,
	std::unique_ptr<DiscardableSharedMemoryHeap::Span> span)
	: manager_(manager), span_(std::move(span)), is_locked_(true) {}

	~DiscardableMemoryImpl() override {
	if (is_locked_)
	manager_->UnlockSpan(span_.get());

	manager_->ReleaseSpan(std::move(span_));
	}

	// Overridden from base::DiscardableMemory:
	bool Lock() override {
	DCHECK(!is_locked_);

	if (!manager_->LockSpan(span_.get()))
	return false;

	is_locked_ = true;
	return true;
	}
	void Unlock() override {
	DCHECK(is_locked_);

	manager_->UnlockSpan(span_.get());
	is_locked_ = false;
	}
	void* data() const override {
	DCHECK(is_locked_);
	return reinterpret_cast<void>(span_->start() base::GetPageSize());
	}

	base::trace_event::MemoryAllocatorDump* CreateMemoryAllocatorDump(
	const char* name,
	base::trace_event::ProcessMemoryDump* pmd) const override {
	return manager_->CreateMemoryAllocatorDump(span_.get(), name, pmd);
	}

	private:
	ChildDiscardableSharedMemoryManager* const manager_;
	std::unique_ptr<DiscardableSharedMemoryHeap::Span> span_;
	bool is_locked_;

	DISALLOW_COPY_AND_ASSIGN(DiscardableMemoryImpl);
	};

	void SendDeletedDiscardableSharedMemoryMessage(
	scoped_refptr<ThreadSafeSender> sender,
	DiscardableSharedMemoryId id) {
	sender->Send(new ChildProcessHostMsg_DeletedDiscardableSharedMemory(id));
	}

	} // namespace

	ChildDiscardableSharedMemoryManager::ChildDiscardableSharedMemoryManager(
	ThreadSafeSender* sender)
	: heap_(base::GetPageSize()), sender_(sender) {
	base::trace_event::MemoryDumpManager::GetInstance()->RegisterDumpProvider(
	this, "ChildDiscardableSharedMemoryManager",
	base::ThreadTaskRunnerHandle::Get());
	}

	ChildDiscardableSharedMemoryManager::~ChildDiscardableSharedMemoryManager() {
	base::trace_event::MemoryDumpManager::GetInstance()->UnregisterDumpProvider(
	this);
	// TODO(reveman): Determine if this DCHECK can be enabled. crbug.com/430533
	// DCHECK_EQ(heap_.GetSize(), heap_.GetSizeOfFreeLists());
	if (heap_.GetSize())
	MemoryUsageChanged(0, 0);
	}

	std::unique_ptr<base::DiscardableMemory>
	ChildDiscardableSharedMemoryManager::AllocateLockedDiscardableMemory(
	size_t size) {
	base::AutoLock lock(lock_);

	// TODO(reveman): Temporary diagnostics for http://crbug.com/577786.
	CHECK_NE(size, 0u);

	UMA_HISTOGRAM_CUSTOM_COUNTS("Memory.DiscardableAllocationSize",
	size / 1024, // In KB
	1,
	4 * 1024 * 1024, // 4 GB
	50);

	// Round up to multiple of page size.
	size_t pages =
	std::max((size + base::GetPageSize() - 1) / base::GetPageSize(),
	static_cast<size_t>(1));

	// Default allocation size in pages.
	size_t allocation_pages = kAllocationSize / base::GetPageSize();

	size_t slack = 0;
	// When searching the free lists, allow a slack between required size and
	// free span size that is less or equal to kAllocationSize. This is to
	// avoid segments larger then kAllocationSize unless they are a perfect
	// fit. The result is that large allocations can be reused without reducing
	// the ability to discard memory.
	if (pages < allocation_pages)
	slack = allocation_pages - pages;

	size_t heap_size_prior_to_releasing_purged_memory = heap_.GetSize();
	for (;;) {
	// Search free lists for suitable span.
	std::unique_ptr<DiscardableSharedMemoryHeap::Span> free_span =
	heap_.SearchFreeLists(pages, slack);
	if (!free_span.get())
	break;

	// Attempt to lock \|free_span\|. Delete span and search free lists again
	// if locking failed.
	if (free_span->shared_memory()->Lock(
	free_span->start() * base::GetPageSize() -
	reinterpret_cast<size_t>(free_span->shared_memory()->memory()),
	free_span->length() * base::GetPageSize()) ==
	base::DiscardableSharedMemory::FAILED) {
	DCHECK(!free_span->shared_memory()->IsMemoryResident());
	// We have to release purged memory before \|free_span\| can be destroyed.
	heap_.ReleasePurgedMemory();
	DCHECK(!free_span->shared_memory());
	continue;
	}

	free_span->set_is_locked(true);

	// Memory usage is guaranteed to have changed after having removed
	// at least one span from the free lists.
	MemoryUsageChanged(heap_.GetSize(), heap_.GetSizeOfFreeLists());

	return base::WrapUnique(
	new DiscardableMemoryImpl(this, std::move(free_span)));
	}

	// Release purged memory to free up the address space before we attempt to
	// allocate more memory.
	heap_.ReleasePurgedMemory();

	// Make sure crash keys are up to date in case allocation fails.
	if (heap_.GetSize() != heap_size_prior_to_releasing_purged_memory)
	MemoryUsageChanged(heap_.GetSize(), heap_.GetSizeOfFreeLists());

	size_t pages_to_allocate =
	std::max(kAllocationSize / base::GetPageSize(), pages);
	size_t allocation_size_in_bytes = pages_to_allocate * base::GetPageSize();

	DiscardableSharedMemoryId new_id =
	g_next_discardable_shared_memory_id.GetNext();

	// Ask parent process to allocate a new discardable shared memory segment.
	std::unique_ptr<base::DiscardableSharedMemory> shared_memory(
	AllocateLockedDiscardableSharedMemory(allocation_size_in_bytes, new_id));

	// Create span for allocated memory.
	std::unique_ptr<DiscardableSharedMemoryHeap::Span> new_span(heap_.Grow(
	std::move(shared_memory), allocation_size_in_bytes, new_id,
	base::Bind(&SendDeletedDiscardableSharedMemoryMessage, sender_, new_id)));
	new_span->set_is_locked(true);

	// Unlock and insert any left over memory into free lists.
	if (pages < pages_to_allocate) {
	std::unique_ptr<DiscardableSharedMemoryHeap::Span> leftover =
	heap_.Split(new_span.get(), pages);
	leftover->shared_memory()->Unlock(
	leftover->start() * base::GetPageSize() -
	reinterpret_cast<size_t>(leftover->shared_memory()->memory()),
	leftover->length() * base::GetPageSize());
	leftover->set_is_locked(false);
	heap_.MergeIntoFreeLists(std::move(leftover));
	}

	MemoryUsageChanged(heap_.GetSize(), heap_.GetSizeOfFreeLists());

	return base::WrapUnique(new DiscardableMemoryImpl(this, std::move(new_span)));
	}

	bool ChildDiscardableSharedMemoryManager::OnMemoryDump(
	const base::trace_event::MemoryDumpArgs& args,
	base::trace_event::ProcessMemoryDump* pmd) {
	base::AutoLock lock(lock_);
	return heap_.OnMemoryDump(pmd);
	}

	void ChildDiscardableSharedMemoryManager::ReleaseFreeMemory() {
	base::AutoLock lock(lock_);

	size_t heap_size_prior_to_releasing_memory = heap_.GetSize();

	// Release both purged and free memory.
	heap_.ReleasePurgedMemory();
	heap_.ReleaseFreeMemory();

	if (heap_.GetSize() != heap_size_prior_to_releasing_memory)
	MemoryUsageChanged(heap_.GetSize(), heap_.GetSizeOfFreeLists());
	}

	bool ChildDiscardableSharedMemoryManager::LockSpan(
	DiscardableSharedMemoryHeap::Span* span) {
	base::AutoLock lock(lock_);

	if (!span->shared_memory())
	return false;

	size_t offset = span->start() * base::GetPageSize() -
	reinterpret_cast<size_t>(span->shared_memory()->memory());
	size_t length = span->length() * base::GetPageSize();

	switch (span->shared_memory()->Lock(offset, length)) {
	case base::DiscardableSharedMemory::SUCCESS:
	span->set_is_locked(true);
	return true;
	case base::DiscardableSharedMemory::PURGED:
	span->shared_memory()->Unlock(offset, length);
	span->set_is_locked(false);
	return false;
	case base::DiscardableSharedMemory::FAILED:
	return false;
	}

	NOTREACHED();
	return false;
	}

	void ChildDiscardableSharedMemoryManager::UnlockSpan(
	DiscardableSharedMemoryHeap::Span* span) {
	base::AutoLock lock(lock_);

	DCHECK(span->shared_memory());
	size_t offset = span->start() * base::GetPageSize() -
	reinterpret_cast<size_t>(span->shared_memory()->memory());
	size_t length = span->length() * base::GetPageSize();

	span->set_is_locked(false);
	return span->shared_memory()->Unlock(offset, length);
	}

	void ChildDiscardableSharedMemoryManager::ReleaseSpan(
	std::unique_ptr<DiscardableSharedMemoryHeap::Span> span) {
	base::AutoLock lock(lock_);

	// Delete span instead of merging it into free lists if memory is gone.
	if (!span->shared_memory())
	return;

	heap_.MergeIntoFreeLists(std::move(span));

	// Bytes of free memory changed.
	MemoryUsageChanged(heap_.GetSize(), heap_.GetSizeOfFreeLists());
	}

	base::trace_event::MemoryAllocatorDump*
	ChildDiscardableSharedMemoryManager::CreateMemoryAllocatorDump(
	DiscardableSharedMemoryHeap::Span* span,
	const char* name,
	base::trace_event::ProcessMemoryDump* pmd) const {
	base::AutoLock lock(lock_);
	return heap_.CreateMemoryAllocatorDump(span, name, pmd);
	}

	std::unique_ptr<base::DiscardableSharedMemory>
	ChildDiscardableSharedMemoryManager::AllocateLockedDiscardableSharedMemory(
	size_t size,
	DiscardableSharedMemoryId id) {
	TRACE_EVENT2("renderer",
	"ChildDiscardableSharedMemoryManager::"
	"AllocateLockedDiscardableSharedMemory",
	"size", size, "id", id);

	base::SharedMemoryHandle handle = base::SharedMemory::NULLHandle();
	sender_->Send(
	new ChildProcessHostMsg_SyncAllocateLockedDiscardableSharedMemory(
	size, id, &handle));
	std::unique_ptr<base::DiscardableSharedMemory> memory(
	new base::DiscardableSharedMemory(handle));
	if (!memory->Map(size))
	base::TerminateBecauseOutOfMemory(size);
	return memory;
	}

	void ChildDiscardableSharedMemoryManager::MemoryUsageChanged(
	size_t new_bytes_total,
	size_t new_bytes_free) const {
	static const char kDiscardableMemoryAllocatedKey[] =
	"discardable-memory-allocated";
	base::debug::SetCrashKeyValue(kDiscardableMemoryAllocatedKey,
	base::Uint64ToString(new_bytes_total));

	static const char kDiscardableMemoryFreeKey[] = "discardable-memory-free";
	base::debug::SetCrashKeyValue(kDiscardableMemoryFreeKey,
	base::Uint64ToString(new_bytes_free));
	}

	} // namespace content