media/blink/webencryptedmediaclient_impl.cc

// 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 "media/blink/webencryptedmediaclient_impl.h"

#include <utility>

#include "base/bind.h"
#include "base/memory/ptr_util.h"
#include "base/metrics/histogram.h"
#include "base/strings/string_util.h"
#include "base/strings/utf_string_conversions.h"
#include "media/base/key_systems.h"
#include "media/base/media_log.h"
#include "media/base/media_permission.h"
#include "media/blink/webcontentdecryptionmodule_impl.h"
#include "media/blink/webcontentdecryptionmoduleaccess_impl.h"
#include "third_party/WebKit/public/platform/URLConversion.h"
#include "third_party/WebKit/public/platform/WebContentDecryptionModuleResult.h"
#include "third_party/WebKit/public/platform/WebEncryptedMediaRequest.h"
#include "third_party/WebKit/public/platform/WebMediaKeySystemConfiguration.h"
#include "third_party/WebKit/public/platform/WebSecurityOrigin.h"
#include "third_party/WebKit/public/platform/WebString.h"
#include "url/gurl.h"
#include "url/origin.h"

namespace media {

namespace {

// Used to name UMAs in Reporter.
const char kKeySystemSupportUMAPrefix[] =
    "Media.EME.RequestMediaKeySystemAccess.";

}  // namespace

// Report usage of key system to UMA. There are 2 different counts logged:
// 1. The key system is requested.
// 2. The requested key system and options are supported.
// Each stat is only reported once per renderer frame per key system.
// Note that WebEncryptedMediaClientImpl is only created once by each
// renderer frame.
class WebEncryptedMediaClientImpl::Reporter {
 public:
  enum KeySystemSupportStatus {
    KEY_SYSTEM_REQUESTED = 0,
    KEY_SYSTEM_SUPPORTED = 1,
    KEY_SYSTEM_SUPPORT_STATUS_COUNT
  };

  explicit Reporter(const std::string& key_system_for_uma)
      : uma_name_(kKeySystemSupportUMAPrefix + key_system_for_uma),
        is_request_reported_(false),
        is_support_reported_(false) {}
  ~Reporter() {}

  void ReportRequested() {
    if (is_request_reported_)
      return;
    Report(KEY_SYSTEM_REQUESTED);
    is_request_reported_ = true;
  }

  void ReportSupported() {
    DCHECK(is_request_reported_);
    if (is_support_reported_)
      return;
    Report(KEY_SYSTEM_SUPPORTED);
    is_support_reported_ = true;
  }

 private:
  void Report(KeySystemSupportStatus status) {
    // Not using UMA_HISTOGRAM_ENUMERATION directly because UMA_* macros
    // require the names to be constant throughout the process' lifetime.
    base::LinearHistogram::FactoryGet(
        uma_name_, 1, KEY_SYSTEM_SUPPORT_STATUS_COUNT,
        KEY_SYSTEM_SUPPORT_STATUS_COUNT + 1,
        base::Histogram::kUmaTargetedHistogramFlag)->Add(status);
  }

  const std::string uma_name_;
  bool is_request_reported_;
  bool is_support_reported_;
};

WebEncryptedMediaClientImpl::WebEncryptedMediaClientImpl(
    CdmFactory* cdm_factory,
    MediaPermission* media_permission,
    MediaLog* media_log)
    : cdm_factory_(cdm_factory),
      key_system_config_selector_(KeySystems::GetInstance(), media_permission),
      media_log_(media_log),
      weak_factory_(this) {
  DCHECK(cdm_factory_);
}

WebEncryptedMediaClientImpl::~WebEncryptedMediaClientImpl() {
}

void WebEncryptedMediaClientImpl::RequestMediaKeySystemAccess(
    blink::WebEncryptedMediaRequest request) {
  GetReporter(request.KeySystem())->ReportRequested();

  media_log_->RecordRapporWithSecurityOrigin("Media.OriginUrl.EME");
  if (!request.GetSecurityOrigin().IsPotentiallyTrustworthy()) {
    media_log_->RecordRapporWithSecurityOrigin("Media.OriginUrl.EME.Insecure");
  }

  key_system_config_selector_.SelectConfig(
      request.KeySystem(), request.SupportedConfigurations(),
      request.GetSecurityOrigin(),
      base::Bind(&WebEncryptedMediaClientImpl::OnRequestSucceeded,
                 weak_factory_.GetWeakPtr(), request),
      base::Bind(&WebEncryptedMediaClientImpl::OnRequestNotSupported,
                 weak_factory_.GetWeakPtr(), request));
}

void WebEncryptedMediaClientImpl::CreateCdm(
    const blink::WebString& key_system,
    const blink::WebSecurityOrigin& security_origin,
    const CdmConfig& cdm_config,
    std::unique_ptr<blink::WebContentDecryptionModuleResult> result) {
  WebContentDecryptionModuleImpl::Create(cdm_factory_, key_system.Utf16(),
                                         security_origin, cdm_config,
                                         std::move(result));
}

void WebEncryptedMediaClientImpl::OnRequestSucceeded(
    blink::WebEncryptedMediaRequest request,
    const blink::WebMediaKeySystemConfiguration& accumulated_configuration,
    const CdmConfig& cdm_config) {
  GetReporter(request.KeySystem())->ReportSupported();
  // TODO(sandersd): Pass |are_secure_codecs_required| along and use it to
  // configure the CDM security level and use of secure surfaces on Android.

  // If the frame is closed while the permission prompt is displayed,
  // the permission prompt is dismissed and this may result in the
  // requestMediaKeySystemAccess request succeeding. However, the blink
  // objects may have been cleared, so check if this is the case and simply
  // reject the request.
  blink::WebSecurityOrigin origin = request.GetSecurityOrigin();
  if (origin.IsNull()) {
    request.RequestNotSupported("Unable to create MediaKeySystemAccess");
    return;
  }

  request.RequestSucceeded(WebContentDecryptionModuleAccessImpl::Create(
      request.KeySystem(), origin, accumulated_configuration, cdm_config,
      weak_factory_.GetWeakPtr()));
}

void WebEncryptedMediaClientImpl::OnRequestNotSupported(
    blink::WebEncryptedMediaRequest request,
    const blink::WebString& error_message) {
  request.RequestNotSupported(error_message);
}

WebEncryptedMediaClientImpl::Reporter* WebEncryptedMediaClientImpl::GetReporter(
    const blink::WebString& key_system) {
  // Assumes that empty will not be found by GetKeySystemNameForUMA().
  // TODO(sandersd): Avoid doing ASCII conversion more than once.
  std::string key_system_ascii;
  if (key_system.ContainsOnlyASCII())
    key_system_ascii = key_system.Ascii();

  // Return a per-frame singleton so that UMA reports will be once-per-frame.
  std::string uma_name = GetKeySystemNameForUMA(key_system_ascii);
  std::unique_ptr<Reporter>& reporter = reporters_[uma_name];
  if (!reporter)
    reporter = base::MakeUnique<Reporter>(uma_name);
  return reporter.get();
}

}  // namespace media