media: CdmFactory creates CDM (MediaKeys) asynchronously.

media/blink/cdm_session_adapter.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/cdm_session_adapter.h"
 
 #include "base/bind.h"
 #include "base/logging.h"
 #include "base/memory/weak_ptr.h"
 #include "base/stl_util.h"
 #include "media/base/cdm_factory.h"
 #include "media/base/cdm_key_information.h"
 #include "media/base/cdm_promise.h"
 #include "media/base/key_systems.h"
 #include "media/base/media_keys.h"
+#include "media/blink/webcontentdecryptionmodule_impl.h"
 #include "media/blink/webcontentdecryptionmodulesession_impl.h"
 #include "url/gurl.h"
 
 namespace media {
 
 const char kMediaEME[] = "Media.EME.";
 const char kDot[] = ".";
 
 CdmSessionAdapter::CdmSessionAdapter() : weak_ptr_factory_(this) {
 }
 
 CdmSessionAdapter::~CdmSessionAdapter() {}
 
-bool CdmSessionAdapter::Initialize(CdmFactory* cdm_factory,
-                                   const std::string& key_system,
-                                   bool allow_distinctive_identifier,
-                                   bool allow_persistent_state,
-                                   const GURL& security_origin) {
-  key_system_ = key_system;
-  key_system_uma_prefix_ =
-      kMediaEME + GetKeySystemNameForUMA(key_system) + kDot;
-
+void CdmSessionAdapter::CreateCdm(
+    CdmFactory* cdm_factory,
+    const std::string& key_system,
+    bool allow_distinctive_identifier,
+    bool allow_persistent_state,
+    const GURL& security_origin,
+    blink::WebContentDecryptionModuleResult result) {
+  // Note: OnCdmCreated() is binded with |this| instead of |weak_this| to
+  // prevent |this| from being desctructed.

[ddorwin, 2015/04/10 00:59:43]

Thanks for documenting this.
Can you further explain why we need to prevent that?

[xhwang, 2015/04/10 17:41:17]

Done.

   base::WeakPtr<CdmSessionAdapter> weak_this = weak_ptr_factory_.GetWeakPtr();
-  media_keys_ = cdm_factory->Create(
+  cdm_factory->Create(
       key_system, allow_distinctive_identifier, allow_persistent_state,
       security_origin,
       base::Bind(&CdmSessionAdapter::OnSessionMessage, weak_this),
       base::Bind(&CdmSessionAdapter::OnSessionClosed, weak_this),
       base::Bind(&CdmSessionAdapter::OnLegacySessionError, weak_this),
       base::Bind(&CdmSessionAdapter::OnSessionKeysChange, weak_this),
-      base::Bind(&CdmSessionAdapter::OnSessionExpirationUpdate, weak_this));
-  return media_keys_.get() != nullptr;
+      base::Bind(&CdmSessionAdapter::OnSessionExpirationUpdate, weak_this),
+      base::Bind(&CdmSessionAdapter::OnCdmCreated, this, key_system, result));
 }
 
 void CdmSessionAdapter::SetServerCertificate(
     const uint8* server_certificate,
     int server_certificate_length,
     scoped_ptr<SimpleCdmPromise> promise) {
-  media_keys_->SetServerCertificate(
-      server_certificate, server_certificate_length, promise.Pass());
+  cdm_->SetServerCertificate(server_certificate, server_certificate_length,
+                             promise.Pass());
 }
 
 WebContentDecryptionModuleSessionImpl* CdmSessionAdapter::CreateSession() {
   return new WebContentDecryptionModuleSessionImpl(this);
 }
 
 bool CdmSessionAdapter::RegisterSession(
     const std::string& session_id,
     base::WeakPtr<WebContentDecryptionModuleSessionImpl> session) {
   // If this session ID is already registered, don't register it again.
   if (ContainsKey(sessions_, session_id))
     return false;
 
   sessions_[session_id] = session;
   return true;
 }
 
 void CdmSessionAdapter::UnregisterSession(const std::string& session_id) {
   DCHECK(ContainsKey(sessions_, session_id));
   sessions_.erase(session_id);
 }
 
 void CdmSessionAdapter::InitializeNewSession(
     EmeInitDataType init_data_type,
     const uint8* init_data,
     int init_data_length,
     MediaKeys::SessionType session_type,
     scoped_ptr<NewSessionCdmPromise> promise) {
-  media_keys_->CreateSessionAndGenerateRequest(session_type, init_data_type,
-                                               init_data, init_data_length,
-                                               promise.Pass());
+  cdm_->CreateSessionAndGenerateRequest(session_type, init_data_type, init_data,
+                                        init_data_length, promise.Pass());
 }
 
 void CdmSessionAdapter::LoadSession(MediaKeys::SessionType session_type,
                                     const std::string& session_id,
                                     scoped_ptr<NewSessionCdmPromise> promise) {
-  media_keys_->LoadSession(session_type, session_id, promise.Pass());
+  cdm_->LoadSession(session_type, session_id, promise.Pass());
 }
 
 void CdmSessionAdapter::UpdateSession(const std::string& session_id,
                                       const uint8* response,
                                       int response_length,
                                       scoped_ptr<SimpleCdmPromise> promise) {
-  media_keys_->UpdateSession(session_id, response, response_length,
-                             promise.Pass());
+  cdm_->UpdateSession(session_id, response, response_length, promise.Pass());
 }
 
 void CdmSessionAdapter::CloseSession(const std::string& session_id,
                                      scoped_ptr<SimpleCdmPromise> promise) {
-  media_keys_->CloseSession(session_id, promise.Pass());
+  cdm_->CloseSession(session_id, promise.Pass());
 }
 
 void CdmSessionAdapter::RemoveSession(const std::string& session_id,
                                       scoped_ptr<SimpleCdmPromise> promise) {
-  media_keys_->RemoveSession(session_id, promise.Pass());
+  cdm_->RemoveSession(session_id, promise.Pass());
 }
 
 CdmContext* CdmSessionAdapter::GetCdmContext() {
-  return media_keys_->GetCdmContext();
+  return cdm_->GetCdmContext();
 }
 
 const std::string& CdmSessionAdapter::GetKeySystem() const {
   return key_system_;
 }
 
 const std::string& CdmSessionAdapter::GetKeySystemUMAPrefix() const {
   return key_system_uma_prefix_;
 }
 
+void CdmSessionAdapter::OnCdmCreated(
+    const std::string& key_system,
+    blink::WebContentDecryptionModuleResult result,
+    scoped_ptr<MediaKeys> cdm) {
+  DVLOG(2) << __FUNCTION__;
+  if (!cdm) {
+    result.completeWithError(
+        blink::WebContentDecryptionModuleExceptionNotSupportedError, 0,
+        "Failed to create CDM.");

[ddorwin, 2015/04/10 00:59:43]

s/CDM/{MediaKeys|CDM instance}/

[xhwang, 2015/04/10 17:41:17]

Done.

+    return;
+  }
+
+  key_system_ = key_system;
+  key_system_uma_prefix_ =
+      kMediaEME + GetKeySystemNameForUMA(key_system) + kDot;
+  cdm_ = cdm.Pass();
+
+  result.completeWithContentDecryptionModule(
+      new WebContentDecryptionModuleImpl(this));
+}
+
 void CdmSessionAdapter::OnSessionMessage(
     const std::string& session_id,
     MediaKeys::MessageType message_type,
     const std::vector<uint8>& message,
     const GURL& /* legacy_destination_url */) {
   WebContentDecryptionModuleSessionImpl* session = GetSession(session_id);
   DLOG_IF(WARNING, !session) << __FUNCTION__ << " for unknown session "
                              << session_id;
   if (session)
     session->OnSessionMessage(message_type, message);
@@ skipping 40 matching lines @@
 WebContentDecryptionModuleSessionImpl* CdmSessionAdapter::GetSession(
     const std::string& session_id) {
   // Since session objects may get garbage collected, it is possible that there
   // are events coming back from the CDM and the session has been unregistered.
   // We can not tell if the CDM is firing events at sessions that never existed.
   SessionMap::iterator session = sessions_.find(session_id);
   return (session != sessions_.end()) ? session->second.get() : NULL;
 }
 
 }  // namespace media