Extract requestMediaKeySystemAccess() algorithm.

media/blink/webencryptedmediaclient_impl.cc

Index: media/blink/webencryptedmediaclient_impl.cc
diff --git a/media/blink/webencryptedmediaclient_impl.cc b/media/blink/webencryptedmediaclient_impl.cc
index 3e64334d67b438c386b42b37b0b716db44b1e050..57902485aa58b5e10e49787a884c88ca1625868a 100644
--- a/media/blink/webencryptedmediaclient_impl.cc
+++ b/media/blink/webencryptedmediaclient_impl.cc
@@ -5,7 +5,6 @@
 #include "webencryptedmediaclient_impl.h"
 
 #include "base/bind.h"
-#include "base/logging.h"
 #include "base/metrics/histogram.h"
 #include "base/strings/string_util.h"
 #include "base/strings/utf_string_conversions.h"
@@ -13,535 +12,20 @@
 #include "media/base/media_permission.h"
 #include "media/blink/webcontentdecryptionmodule_impl.h"
 #include "media/blink/webcontentdecryptionmoduleaccess_impl.h"
-#include "media/blink/webmediaplayer_util.h"
-#include "net/base/mime_util.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/WebString.h"
-#include "third_party/WebKit/public/platform/WebVector.h"
 
 namespace media {
 
-// These names are used by UMA.
+namespace {
+
+// Used to name UMAs in Reporter.
 const char kKeySystemSupportUMAPrefix[] =
     "Media.EME.RequestMediaKeySystemAccess.";
 
-enum ConfigurationSupport {
-  CONFIGURATION_NOT_SUPPORTED,
-  CONFIGURATION_REQUIRES_PERMISSION,
-  CONFIGURATION_SUPPORTED,
-};
-
-// Accumulates configuration rules to determine if a feature (additional
-// configuration rule) can be added to an accumulated configuration.
-class ConfigState {
- public:
-  ConfigState(bool was_permission_requested, bool is_permission_granted)
-      : was_permission_requested_(was_permission_requested),
-        is_permission_granted_(is_permission_granted) {
-  }
-
-  bool IsPermissionGranted() const {
-    return is_permission_granted_;
-  }
-
-  // Permission is possible if it has not been denied.
-  bool IsPermissionPossible() const {
-    return is_permission_granted_ || !was_permission_requested_;
-  }
-
-  bool IsIdentifierRequired() const {
-    return is_identifier_required_;
-  }
-
-  bool IsIdentifierRecommended() const {
-    return is_identifier_recommended_;
-  }
-
-  // Checks whether a rule is compatible with all previously added rules.
-  bool IsRuleSupported(EmeConfigRule rule) const {
-    switch (rule) {
-      case EmeConfigRule::NOT_SUPPORTED:
-        return false;
-      case EmeConfigRule::IDENTIFIER_NOT_ALLOWED:
-        return !is_identifier_required_;
-      case EmeConfigRule::IDENTIFIER_REQUIRED:
-        // TODO(sandersd): Confirm if we should be refusing these rules when
-        // permission has been denied (as the spec currently says).
-        return !is_identifier_not_allowed_ && IsPermissionPossible();
-      case EmeConfigRule::IDENTIFIER_RECOMMENDED:
-        return true;
-      case EmeConfigRule::PERSISTENCE_NOT_ALLOWED:
-        return !is_persistence_required_;
-      case EmeConfigRule::PERSISTENCE_REQUIRED:
-        return !is_persistence_not_allowed_;
-      case EmeConfigRule::IDENTIFIER_AND_PERSISTENCE_REQUIRED:
-        return (!is_identifier_not_allowed_ && IsPermissionPossible() &&
-                !is_persistence_not_allowed_);
-      case EmeConfigRule::SUPPORTED:
-        return true;
-    }
-    NOTREACHED();
-    return false;
-  }
-
-  // Add a rule to the accumulated configuration state.
-  void AddRule(EmeConfigRule rule) {
-    DCHECK(IsRuleSupported(rule));
-    switch (rule) {
-      case EmeConfigRule::NOT_SUPPORTED:
-        return;
-      case EmeConfigRule::IDENTIFIER_NOT_ALLOWED:
-        is_identifier_not_allowed_ = true;
-        return;
-      case EmeConfigRule::IDENTIFIER_REQUIRED:
-        is_identifier_required_ = true;
-        return;
-      case EmeConfigRule::IDENTIFIER_RECOMMENDED:
-        is_identifier_recommended_ = true;
-        return;
-      case EmeConfigRule::PERSISTENCE_NOT_ALLOWED:
-        is_persistence_not_allowed_ = true;
-        return;
-      case EmeConfigRule::PERSISTENCE_REQUIRED:
-        is_persistence_required_ = true;
-        return;
-      case EmeConfigRule::IDENTIFIER_AND_PERSISTENCE_REQUIRED:
-        is_identifier_required_ = true;
-        is_persistence_required_ = true;
-        return;
-      case EmeConfigRule::SUPPORTED:
-        return;
-    }
-    NOTREACHED();
-  }
-
- private:
-  // Whether permission to use a distinctive identifier was requested. If set,
-  // |is_permission_granted_| represents the final decision.
-  const bool was_permission_requested_;
-
-  // Whether permission to use a distinctive identifier has been granted.
-  const bool is_permission_granted_;
-
-  // Whether a rule has been added that requires or blocks a distinctive
-  // identifier.
-  bool is_identifier_required_ = false;
-  bool is_identifier_not_allowed_ = false;
-
-  // Whether a rule has been added that recommends a distinctive identifier.
-  bool is_identifier_recommended_ = false;
-
-  // Whether a rule has been added that requires or blocks persistent state.
-  bool is_persistence_required_ = false;
-  bool is_persistence_not_allowed_ = false;
-};
-
-static bool IsSupportedContentType(
-    const KeySystems& key_systems,
-    const std::string& key_system,
-    EmeMediaType media_type,
-    const std::string& container_mime_type,
-    const std::string& codecs) {
-  // TODO(sandersd): Move contentType parsing from Blink to here so that invalid
-  // parameters can be rejected. http://crbug.com/417561
-  std::string container_lower = base::StringToLowerASCII(container_mime_type);
-
-  // Check that |container_mime_type| and |codecs| are supported by the CDM.
-  // This check does not handle extended codecs, so extended codec information
-  // is stripped.
-  std::vector<std::string> codec_vector;
-  net::ParseCodecString(codecs, &codec_vector, true);
-  if (!key_systems.IsSupportedCodecCombination(
-           key_system, media_type, container_lower, codec_vector)) {
-    return false;
-  }
-
-  // Check that |container_mime_type| is supported by Chrome. This can only
-  // happen if the CDM declares support for a container that Chrome does not.
-  if (!net::IsSupportedMediaMimeType(container_lower)) {
-    NOTREACHED();
-    return false;
-  }
-
-  // Check that |codecs| are supported by Chrome. This is done primarily to
-  // validate extended codecs, but it also ensures that the CDM cannot support
-  // codecs that Chrome does not (which could complicate the robustness
-  // algorithm).
-  if (codec_vector.empty())
-    return true;
-  codec_vector.clear();
-  net::ParseCodecString(codecs, &codec_vector, false);
-  return (net::IsSupportedStrictMediaMimeType(container_lower, codec_vector) ==
-          net::IsSupported);
-}
-
-static bool GetSupportedCapabilities(
-    const KeySystems& key_systems,
-    const std::string& key_system,
-    EmeMediaType media_type,
-    const blink::WebVector<blink::WebMediaKeySystemMediaCapability>&
-        requested_media_capabilities,
-    ConfigState* config_state,
-    std::vector<blink::WebMediaKeySystemMediaCapability>*
-        supported_media_capabilities) {
-  // From
-  // https://w3c.github.io/encrypted-media/#get-supported-capabilities-for-media-type
-  // 1. Let local accumulated capabilities be a local copy of partial
-  //    configuration.
-  //    (Skipped as we directly update |config_state|. This is safe because we
-  //    only do so when at least one requested media capability is supported.)
-  // 2. Let supported media capabilities be empty.
-  DCHECK_EQ(supported_media_capabilities->size(), 0ul);
-  // 3. For each value in requested media capabilities:
-  for (size_t i = 0; i < requested_media_capabilities.size(); i++) {
-    // 3.1. Let contentType be the value's contentType member.
-    // 3.2. Let robustness be the value's robustness member.
-    const blink::WebMediaKeySystemMediaCapability& capability =
-        requested_media_capabilities[i];
-    // 3.3. If contentType is the empty string, return null.
-    if (capability.mimeType.isEmpty()) {
-      DVLOG(2) << "Rejecting requested configuration because "
-               << "a capability contentType was empty.";
-      return false;
-    }
-    // 3.4-3.11. (Implemented by IsSupportedContentType().)
-    if (!base::IsStringASCII(capability.mimeType) ||
-        !base::IsStringASCII(capability.codecs) ||
-        !IsSupportedContentType(key_systems, key_system, media_type,
-                                base::UTF16ToASCII(capability.mimeType),
-                                base::UTF16ToASCII(capability.codecs))) {
-      continue;
-    }
-    // 3.12. If robustness is not the empty string, run the following steps:
-    if (!capability.robustness.isEmpty()) {
-      // 3.12.1. If robustness is an unrecognized value or not supported by
-      //         implementation, continue to the next iteration. String
-      //         comparison is case-sensitive.
-      if (!base::IsStringASCII(capability.robustness))
-        continue;
-      EmeConfigRule robustness_rule = key_systems.GetRobustnessConfigRule(
-          key_system, media_type, base::UTF16ToASCII(capability.robustness));
-      if (!config_state->IsRuleSupported(robustness_rule))
-        continue;
-      config_state->AddRule(robustness_rule);
-      // 3.12.2. Add robustness to configuration.
-      //         (It's already added, we use capability as configuration.)
-    }
-    // 3.13. If the user agent and implementation do not support playback of
-    //       encrypted media data as specified by configuration, including all
-    //       media types, in combination with local accumulated capabilities,
-    //       continue to the next iteration.
-    //       (This is handled when adding rules to |config_state|.)
-    // 3.14. Add configuration to supported media capabilities.
-    supported_media_capabilities->push_back(capability);
-    // 3.15. Add configuration to local accumulated capabilities.
-    //       (Skipped as we directly update |config_state|.)
-  }
-  // 4. If supported media capabilities is empty, return null.
-  if (supported_media_capabilities->empty()) {
-    DVLOG(2) << "Rejecting requested configuration because "
-             << "no capabilities were supported.";
-    return false;
-  }
-  // 5. Return media type capabilities.
-  return true;
-}
-
-static EmeFeatureRequirement ConvertRequirement(
-    blink::WebMediaKeySystemConfiguration::Requirement requirement) {
-  switch (requirement) {
-    case blink::WebMediaKeySystemConfiguration::Requirement::Required:
-      return EME_FEATURE_REQUIRED;
-    case blink::WebMediaKeySystemConfiguration::Requirement::Optional:
-      return EME_FEATURE_OPTIONAL;
-    case blink::WebMediaKeySystemConfiguration::Requirement::NotAllowed:
-      return EME_FEATURE_NOT_ALLOWED;
-  }
-
-  NOTREACHED();
-  return EME_FEATURE_NOT_ALLOWED;
-}
-
-static ConfigurationSupport GetSupportedConfiguration(
-    const KeySystems& key_systems,
-    const std::string& key_system,
-    const blink::WebMediaKeySystemConfiguration& candidate,
-    bool was_permission_requested,
-    bool is_permission_granted,
-    blink::WebMediaKeySystemConfiguration* accumulated_configuration) {
-  ConfigState config_state(was_permission_requested, is_permission_granted);
-
-  // From https://w3c.github.io/encrypted-media/#get-supported-configuration
-  // 1. Let accumulated configuration be empty. (Done by caller.)
-  // 2. If the initDataTypes member is present in candidate configuration, run
-  //    the following steps:
-  if (candidate.hasInitDataTypes) {
-    // 2.1. Let supported types be empty.
-    std::vector<blink::WebEncryptedMediaInitDataType> supported_types;
-
-    // 2.2. For each value in candidate configuration's initDataTypes member:
-    for (size_t i = 0; i < candidate.initDataTypes.size(); i++) {
-      // 2.2.1. Let initDataType be the value.
-      blink::WebEncryptedMediaInitDataType init_data_type =
-          candidate.initDataTypes[i];
-      // 2.2.2. If the implementation supports generating requests based on
-      //        initDataType, add initDataType to supported types. String
-      //        comparison is case-sensitive. The empty string is never
-      //        supported.
-      if (init_data_type == blink::WebEncryptedMediaInitDataType::Unknown)
-        continue;
-      if (key_systems.IsSupportedInitDataType(
-              key_system, ConvertToEmeInitDataType(init_data_type))) {
-        supported_types.push_back(init_data_type);
-      }
-    }
-
-    // 2.3. If supported types is empty, return null.
-    if (supported_types.empty()) {
-      DVLOG(2) << "Rejecting requested configuration because "
-               << "no initDataType values were supported.";
-      return CONFIGURATION_NOT_SUPPORTED;
-    }
-
-    // 2.4. Add supported types to accumulated configuration.
-    accumulated_configuration->initDataTypes = supported_types;
-  }
-
-  // 3. Follow the steps for the value of candidate configuration's
-  //    distinctiveIdentifier attribute from the following list:
-  //      - "required": If the implementation does not support a persistent
-  //        Distinctive Identifier in combination with accumulated
-  //        configuration, return null.
-  //      - "optional": Continue.
-  //      - "not-allowed": If the implementation requires a Distinctive
-  //        Identifier in combination with accumulated configuration, return
-  //        null.
-  // We also reject OPTIONAL when distinctive identifiers are ALWAYS_ENABLED and
-  // permission has already been denied. This would happen anyway at step 11.
-  EmeConfigRule di_rule = key_systems.GetDistinctiveIdentifierConfigRule(
-      key_system, ConvertRequirement(candidate.distinctiveIdentifier));
-  if (!config_state.IsRuleSupported(di_rule)) {
-    DVLOG(2) << "Rejecting requested configuration because "
-             << "the distinctiveIdentifier requirement was not supported.";
-    return CONFIGURATION_NOT_SUPPORTED;
-  }
-  config_state.AddRule(di_rule);
-
-  // 4. Add the value of the candidate configuration's distinctiveIdentifier
-  //    attribute to accumulated configuration.
-  accumulated_configuration->distinctiveIdentifier =
-      candidate.distinctiveIdentifier;
-
-  // 5. Follow the steps for the value of candidate configuration's
-  //    persistentState attribute from the following list:
-  //      - "required": If the implementation does not support persisting state
-  //        in combination with accumulated configuration, return null.
-  //      - "optional": Continue.
-  //      - "not-allowed": If the implementation requires persisting state in
-  //        combination with accumulated configuration, return null.
-  EmeConfigRule ps_rule = key_systems.GetPersistentStateConfigRule(
-      key_system, ConvertRequirement(candidate.persistentState));
-  if (!config_state.IsRuleSupported(ps_rule)) {
-    DVLOG(2) << "Rejecting requested configuration because "
-             << "the persistentState requirement was not supported.";
-    return CONFIGURATION_NOT_SUPPORTED;
-  }
-  config_state.AddRule(ps_rule);
-
-  // 6. Add the value of the candidate configuration's persistentState
-  //    attribute to accumulated configuration.
-  accumulated_configuration->persistentState = candidate.persistentState;
-
-  // 7. Follow the steps for the first matching condition from the following
-  //    list:
-  //      - If the sessionTypes member is present in candidate configuration,
-  //        let session types be candidate configuration's sessionTypes member.
-  //      - Otherwise, let session types be [ "temporary" ].
-  blink::WebVector<blink::WebEncryptedMediaSessionType> session_types;
-  if (candidate.hasSessionTypes) {
-    session_types = candidate.sessionTypes;
-  } else {
-    std::vector<blink::WebEncryptedMediaSessionType> temporary(1);
-    temporary[0] = blink::WebEncryptedMediaSessionType::Temporary;
-    session_types = temporary;
-  }
-
-  // 8. For each value in session types:
-  for (size_t i = 0; i < session_types.size(); i++) {
-    // 8.1. Let session type be the value.
-    blink::WebEncryptedMediaSessionType session_type = session_types[i];
-    // 8.2. If the implementation does not support session type in combination
-    //      with accumulated configuration, return null.
-    // 8.3. If session type is "persistent-license" or
-    //      "persistent-release-message", follow the steps for accumulated
-    //      configuration's persistentState value from the following list:
-    //        - "required": Continue.
-    //        - "optional": Change accumulated configuration's persistentState
-    //          value to "required".
-    //        - "not-allowed": Return null.
-    EmeConfigRule session_type_rule = EmeConfigRule::NOT_SUPPORTED;
-    switch (session_type) {
-      case blink::WebEncryptedMediaSessionType::Unknown:
-        DVLOG(2) << "Rejecting requested configuration because "
-                 << "a required session type was not recognized.";
-        return CONFIGURATION_NOT_SUPPORTED;
-      case blink::WebEncryptedMediaSessionType::Temporary:
-        session_type_rule = EmeConfigRule::SUPPORTED;
-        break;
-      case blink::WebEncryptedMediaSessionType::PersistentLicense:
-        session_type_rule =
-            key_systems.GetPersistentLicenseSessionConfigRule(key_system);
-        break;
-      case blink::WebEncryptedMediaSessionType::PersistentReleaseMessage:
-        session_type_rule =
-            key_systems.GetPersistentReleaseMessageSessionConfigRule(
-                key_system);
-        break;
-    }
-    if (!config_state.IsRuleSupported(session_type_rule)) {
-      DVLOG(2) << "Rejecting requested configuration because "
-               << "a required session type was not supported.";
-      return CONFIGURATION_NOT_SUPPORTED;
-    }
-    config_state.AddRule(session_type_rule);
-  }
-
-  // 9. Add session types to accumulated configuration.
-  accumulated_configuration->sessionTypes = session_types;
-
-  // 10. If the videoCapabilities member is present in candidate configuration:
-  if (candidate.hasVideoCapabilities) {
-    // 10.1. Let video capabilities be the result of executing the Get Supported
-    //       Capabilities for Media Type algorithm on Video, candidate
-    //       configuration's videoCapabilities member, and accumulated
-    //       configuration.
-    // 10.2. If video capabilities is null, return null.
-    std::vector<blink::WebMediaKeySystemMediaCapability> video_capabilities;
-    if (!GetSupportedCapabilities(key_systems, key_system, EmeMediaType::VIDEO,
-                                  candidate.videoCapabilities,
-                                  &config_state, &video_capabilities)) {
-      return CONFIGURATION_NOT_SUPPORTED;
-    }
-
-    // 10.3. Add video capabilities to accumulated configuration.
-    accumulated_configuration->videoCapabilities = video_capabilities;
-  }
-
-  // 11. If the audioCapabilities member is present in candidate configuration:
-  if (candidate.hasAudioCapabilities) {
-    // 11.1. Let audio capabilities be the result of executing the Get Supported
-    //       Capabilities for Media Type algorithm on Audio, candidate
-    //       configuration's audioCapabilities member, and accumulated
-    //       configuration.
-    // 11.2. If audio capabilities is null, return null.
-    std::vector<blink::WebMediaKeySystemMediaCapability> audio_capabilities;
-    if (!GetSupportedCapabilities(key_systems, key_system, EmeMediaType::AUDIO,
-                                  candidate.audioCapabilities,
-                                  &config_state, &audio_capabilities)) {
-      return CONFIGURATION_NOT_SUPPORTED;
-    }
-
-    // 11.3. Add audio capabilities to accumulated configuration.
-    accumulated_configuration->audioCapabilities = audio_capabilities;
-  }
-
-  // 12. If accumulated configuration's distinctiveIdentifier value is
-  //     "optional", follow the steps for the first matching condition from the
-  //     following list:
-  //       - If the implementation requires a Distinctive Identifier for any of
-  //         the combinations in accumulated configuration, change accumulated
-  //         configuration's distinctiveIdentifier value to "required".
-  //       - Otherwise, change accumulated configuration's distinctiveIdentifier
-  //         value to "not-allowed".
-  if (accumulated_configuration->distinctiveIdentifier ==
-      blink::WebMediaKeySystemConfiguration::Requirement::Optional) {
-    EmeConfigRule not_allowed_rule =
-        key_systems.GetDistinctiveIdentifierConfigRule(
-            key_system, EME_FEATURE_NOT_ALLOWED);
-    EmeConfigRule required_rule =
-        key_systems.GetDistinctiveIdentifierConfigRule(
-            key_system, EME_FEATURE_REQUIRED);
-    bool not_allowed_supported = config_state.IsRuleSupported(not_allowed_rule);
-    bool required_supported = config_state.IsRuleSupported(required_rule);
-    // If a distinctive identifier is recommend and that is a possible outcome,
-    // prefer that.
-    if (required_supported &&
-        config_state.IsIdentifierRecommended() &&
-        config_state.IsPermissionPossible()) {
-      not_allowed_supported = false;
-    }
-    if (not_allowed_supported) {
-      accumulated_configuration->distinctiveIdentifier =
-          blink::WebMediaKeySystemConfiguration::Requirement::NotAllowed;
-      config_state.AddRule(not_allowed_rule);
-    } else if (required_supported) {
-      accumulated_configuration->distinctiveIdentifier =
-          blink::WebMediaKeySystemConfiguration::Requirement::Required;
-      config_state.AddRule(required_rule);
-    } else {
-      // We should not have passed step 3.
-      NOTREACHED();
-      return CONFIGURATION_NOT_SUPPORTED;
-    }
-  }
-
-  // 13. If accumulated configuration's persistentState value is "optional",
-  //     follow the steps for the first matching condition from the following
-  //     list:
-  //       - If the implementation requires persisting state for any of the
-  //         combinations in accumulated configuration, change accumulated
-  //         configuration's persistentState value to "required".
-  //       - Otherwise, change accumulated configuration's persistentState value
-  //         to "not-allowed".
-  if (accumulated_configuration->persistentState ==
-      blink::WebMediaKeySystemConfiguration::Requirement::Optional) {
-    EmeConfigRule not_allowed_rule =
-        key_systems.GetPersistentStateConfigRule(
-            key_system, EME_FEATURE_NOT_ALLOWED);
-    EmeConfigRule required_rule =
-        key_systems.GetPersistentStateConfigRule(
-            key_system, EME_FEATURE_REQUIRED);
-    // |distinctiveIdentifier| should not be affected after it is decided.
-    DCHECK(not_allowed_rule == EmeConfigRule::NOT_SUPPORTED ||
-           not_allowed_rule == EmeConfigRule::PERSISTENCE_NOT_ALLOWED);
-    DCHECK(required_rule == EmeConfigRule::NOT_SUPPORTED ||
-           required_rule == EmeConfigRule::PERSISTENCE_REQUIRED);
-    bool not_allowed_supported =
-        config_state.IsRuleSupported(not_allowed_rule);
-    bool required_supported =
-        config_state.IsRuleSupported(required_rule);
-    if (not_allowed_supported) {
-      accumulated_configuration->persistentState =
-          blink::WebMediaKeySystemConfiguration::Requirement::NotAllowed;
-      config_state.AddRule(not_allowed_rule);
-    } else if (required_supported) {
-      accumulated_configuration->persistentState =
-          blink::WebMediaKeySystemConfiguration::Requirement::Required;
-      config_state.AddRule(required_rule);
-    } else {
-      // We should not have passed step 5.
-      NOTREACHED();
-      return CONFIGURATION_NOT_SUPPORTED;
-    }
-  }
-
-  // 14. If implementation in the configuration specified by the combination of
-  //     the values in accumulated configuration is not supported or not allowed
-  //     in the origin, return null.
-  // 15. If accumulated configuration's distinctiveIdentifier value is
-  //     "required", [prompt the user for consent].
-  if (accumulated_configuration->distinctiveIdentifier ==
-      blink::WebMediaKeySystemConfiguration::Requirement::Required) {
-    // The caller is responsible for resolving what to do if permission is
-    // required but has been denied (it should treat it as NOT_SUPPORTED).
-    if (!config_state.IsPermissionGranted())
-      return CONFIGURATION_REQUIRES_PERMISSION;
-  }
-
-  // 16. Return accumulated configuration.
-  return CONFIGURATION_SUPPORTED;
-}
+}  // namespace
 
 // Report usage of key system to UMA. There are 2 different counts logged:
 // 1. The key system is requested.
@@ -596,11 +80,9 @@ class WebEncryptedMediaClientImpl::Reporter {
 WebEncryptedMediaClientImpl::WebEncryptedMediaClientImpl(
     scoped_ptr<CdmFactory> cdm_factory,
     MediaPermission* media_permission)
-    : key_systems_(KeySystems::GetInstance()),
-      cdm_factory_(cdm_factory.Pass()),
-      media_permission_(media_permission),
+    : cdm_factory_(cdm_factory.Pass()),
+      key_system_config_selector_(&KeySystems::GetInstance(), media_permission),

[sandersd (OOO until July 31), 2015/04/02 20:37:50]

This makes me think that GetInstance() should return a KeySystems* instead of a
KeySystems&, but it's equally reasonable to store a ref in
KeySystemConfigSelector. WDYT?

[ddorwin, 2015/04/03 22:36:46]

We don't usually store refs to things as members, so this looks correct.

However, I don't know why or whether GetInstance() returns a ref (perhaps
related to or an artifact of the lazy instance pattern or mime_util code
KeySystems was originally adapted from). I'd do whatever seems to be common for
GetInstance(). A quick search seems to indicate returning a pointer is more
common.

       weak_factory_(this) {
-  DCHECK(media_permission);
 }
 
 WebEncryptedMediaClientImpl::~WebEncryptedMediaClientImpl() {
@@ -608,92 +90,15 @@ WebEncryptedMediaClientImpl::~WebEncryptedMediaClientImpl() {
 
 void WebEncryptedMediaClientImpl::requestMediaKeySystemAccess(
     blink::WebEncryptedMediaRequest request) {
-  // TODO(jrummell): This should be asynchronous, ideally not on the main
-  // thread.
-
-  // Continued from requestMediaKeySystemAccess(), step 7, from
-  // https://w3c.github.io/encrypted-media/#requestmediakeysystemaccess
-  //
-  // 7.1. If keySystem is not one of the Key Systems supported by the user
-  //      agent, reject promise with with a new DOMException whose name is
-  //      NotSupportedError. String comparison is case-sensitive.
-  if (!base::IsStringASCII(request.keySystem())) {
-    request.requestNotSupported("Only ASCII keySystems are supported");
-    return;
-  }
-
-  // Report this request to the UMA.
-  std::string key_system = base::UTF16ToASCII(request.keySystem());
-  GetReporter(key_system)->ReportRequested();
-
-  if (!key_systems_.IsSupportedKeySystem(key_system)) {
-    request.requestNotSupported("Unsupported keySystem");
-    return;
-  }
-
-  // 7.2-7.4. Implemented by SelectSupportedConfiguration().
-  SelectSupportedConfiguration(request, false, false);
-}
-
-void WebEncryptedMediaClientImpl::SelectSupportedConfiguration(
-    blink::WebEncryptedMediaRequest request,
-    bool was_permission_requested,
-    bool is_permission_granted) {
-  // Continued from requestMediaKeySystemAccess(), step 7.1, from
-  // https://w3c.github.io/encrypted-media/#requestmediakeysystemaccess
-  //
-  // 7.2. Let implementation be the implementation of keySystem.
-  std::string key_system = base::UTF16ToASCII(request.keySystem());
-
-  // 7.3. For each value in supportedConfigurations:
-  const blink::WebVector<blink::WebMediaKeySystemConfiguration>&
-      configurations = request.supportedConfigurations();
-  for (size_t i = 0; i < configurations.size(); i++) {
-    // 7.3.1. Let candidate configuration be the value.
-    const blink::WebMediaKeySystemConfiguration& candidate_configuration =
-        configurations[i];
-    // 7.3.2. Let supported configuration be the result of executing the Get
-    //        Supported Configuration algorithm on implementation, candidate
-    //        configuration, and origin.
-    // 7.3.3. If supported configuration is not null, [initialize and return a
-    //        new MediaKeySystemAccess object.]
-    blink::WebMediaKeySystemConfiguration accumulated_configuration;
-    ConfigurationSupport supported = GetSupportedConfiguration(
-        key_systems_, key_system, candidate_configuration,
-        was_permission_requested, is_permission_granted,
-        &accumulated_configuration);
-    switch (supported) {
-      case CONFIGURATION_NOT_SUPPORTED:
-        continue;
-      case CONFIGURATION_REQUIRES_PERMISSION:
-        if (was_permission_requested) {
-          DVLOG(2) << "Rejecting requested configuration because "
-                   << "permission was denied.";
-          continue;
-        }
-        media_permission_->RequestPermission(
-            MediaPermission::PROTECTED_MEDIA_IDENTIFIER,
-            GURL(request.securityOrigin().toString()),
-            // Try again with |was_permission_requested| true and
-            // |is_permission_granted| the value of the permission.
-            base::Bind(
-                &WebEncryptedMediaClientImpl::SelectSupportedConfiguration,
-                weak_factory_.GetWeakPtr(), request, true));
-        return;
-      case CONFIGURATION_SUPPORTED:
-        // Report that this request succeeded to the UMA.
-        GetReporter(key_system)->ReportSupported();
-        request.requestSucceeded(WebContentDecryptionModuleAccessImpl::Create(
-            request.keySystem(), accumulated_configuration,
-            request.securityOrigin(), weak_factory_.GetWeakPtr()));
-        return;
-    }
-  }
-
-  // 7.4. Reject promise with a new DOMException whose name is
-  //      NotSupportedError.
-  request.requestNotSupported(
-      "None of the requested configurations were supported.");
+  GetReporter(request.keySystem())->ReportRequested();
+  key_system_config_selector_.SelectConfig(
+      request.keySystem(),
+      request.supportedConfigurations(),
+      request.securityOrigin(),
+      base::Bind(&WebEncryptedMediaClientImpl::OnRequestSucceeded,
+                 weak_factory_.GetWeakPtr(), request),
+      base::Bind(&WebEncryptedMediaClientImpl::OnRequestNotSupported,
+                 weak_factory_.GetWeakPtr(), request));
 }
 
 void WebEncryptedMediaClientImpl::CreateCdm(
@@ -702,25 +107,42 @@ void WebEncryptedMediaClientImpl::CreateCdm(
     bool allow_persistent_state,
     const blink::WebSecurityOrigin& security_origin,
     blink::WebContentDecryptionModuleResult result) {
-  WebContentDecryptionModuleImpl::Create(cdm_factory_.get(), key_system,
-                                         allow_distinctive_identifier,
-                                         allow_persistent_state,
-                                         security_origin, result);
+  WebContentDecryptionModuleImpl::Create(
+      cdm_factory_.get(), key_system, allow_distinctive_identifier,
+      allow_persistent_state, security_origin, result);
+}
+
+void WebEncryptedMediaClientImpl::OnRequestSucceeded(
+    blink::WebEncryptedMediaRequest request,
+    const blink::WebMediaKeySystemConfiguration& accumulated_configuration) {
+  GetReporter(request.keySystem())->ReportSupported();
+  request.requestSucceeded(WebContentDecryptionModuleAccessImpl::Create(
+      request.keySystem(), accumulated_configuration, request.securityOrigin(),
+      weak_factory_.GetWeakPtr()));
+}
+
+void WebEncryptedMediaClientImpl::OnRequestNotSupported(
+    blink::WebEncryptedMediaRequest request,
+    const blink::WebString& error_message) {
+  request.requestNotSupported(error_message);
 }
 
-// Lazily create Reporters.
 WebEncryptedMediaClientImpl::Reporter* WebEncryptedMediaClientImpl::GetReporter(
-    const std::string& key_system) {
-  std::string uma_name = GetKeySystemNameForUMA(key_system);
+    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 (base::IsStringASCII(key_system))
+    key_system_ascii = base::UTF16ToASCII(key_system);
+
+  // Return a singleton so that UMA reports will be once-per-frame.
+  std::string uma_name = GetKeySystemNameForUMA(key_system_ascii);
   Reporter* reporter = reporters_.get(uma_name);
-  if (reporter != nullptr)
-    return reporter;
-
-  // Reporter not found, so create one.
-  auto result =
-      reporters_.add(uma_name, make_scoped_ptr(new Reporter(uma_name)));
-  DCHECK(result.second);
-  return result.first->second;
+  if (!reporter) {
+    reporter = new Reporter(uma_name);
+    reporters_.add(uma_name, make_scoped_ptr(reporter));
+  }
+  return reporter;
 }
 
 }  // namespace media