Prepare MediaDrmBridge to work with MediaCodecPlayer

media/base/android/media_drm_proxy.h

Index: media/base/android/media_drm_proxy.h
diff --git a/media/base/android/media_drm_proxy.h b/media/base/android/media_drm_proxy.h
new file mode 100644
index 0000000000000000000000000000000000000000..35db3a8cea6df7864b5857d724766b34dda562cd
--- /dev/null
+++ b/media/base/android/media_drm_proxy.h
@@ -0,0 +1,139 @@
+// Copyright (c) 2015 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.
+
+#ifndef MEDIA_BASE_ANDROID_MEDIA_DRM_PROXY_H_
+#define MEDIA_BASE_ANDROID_MEDIA_DRM_PROXY_H_
+
+#include <string>
+
+#include "base/memory/scoped_ptr.h"
+#include "base/memory/weak_ptr.h"
+#include "media/base/android/media_drm_bridge.h"
+#include "media/base/browser_cdm.h"
+
+namespace media {
+
+// This class delegates MediaDrmBridge calls onto the Media thread

[ddorwin, 2015/09/16 20:42:21]

This is a lot of duplicate code and extra function calls. Is there a better way
to do this? Could this be handled within the BrowserCdm implementation?

[Tima Vaisburd, 2015/09/18 00:41:38]

I tried a different approach, where only the callbacks necessary for the
MediaCodecPlayer are reposted to the Media thread. The MediaDrmBridge itself is
deleted on the Media thread, too. The code became simpler, there is no need for
a proxy object and there is no thread hopping for other callbacks. I updated the
CL description.

This change might address most of your concerns.

+class MEDIA_EXPORT MediaDrmProxy : public BrowserCdm {

[ddorwin, 2015/09/16 20:42:21]

"Proxy" isn't very descriptive. (We've regretted using that term in the past.)
Is there a better name?

+ public:
+  ~MediaDrmProxy() override;
+  void DeleteOnCorrectThread() override;
+
+  // Returns a MediaDrmBridge instance if |key_system| is supported, or a NULL
+  // pointer otherwise.
+  // TODO(xhwang): Is it okay not to update session expiration info?
+  static scoped_ptr<MediaDrmProxy, BrowserCdmDeleter> Create(
+      const std::string& key_system,
+      MediaDrmBridge::SecurityLevel widevine_security_level,
+      const SessionMessageCB& session_message_cb,
+      const SessionClosedCB& session_closed_cb,
+      const LegacySessionErrorCB& legacy_session_error_cb,
+      const SessionKeysChangeCB& session_keys_change_cb,
+      const SessionExpirationUpdateCB& session_expiration_update_cb);
+
+  // MediaKeys (via BrowserCdm) implementation.
+
+  void SetServerCertificate(
+      const std::vector<uint8_t>& certificate,
+      scoped_ptr<media::SimpleCdmPromise> promise) override;
+  void CreateSessionAndGenerateRequest(
+      SessionType session_type,
+      media::EmeInitDataType init_data_type,
+      const std::vector<uint8_t>& init_data,
+      scoped_ptr<media::NewSessionCdmPromise> promise) override;
+  void LoadSession(SessionType session_type,
+                   const std::string& session_id,
+                   scoped_ptr<media::NewSessionCdmPromise> promise) override;
+  void UpdateSession(const std::string& session_id,
+                     const std::vector<uint8_t>& response,
+                     scoped_ptr<media::SimpleCdmPromise> promise) override;
+  void CloseSession(const std::string& session_id,
+                    scoped_ptr<media::SimpleCdmPromise> promise) override;
+  void RemoveSession(const std::string& session_id,
+                     scoped_ptr<media::SimpleCdmPromise> promise) override;
+  CdmContext* GetCdmContext() override;
+
+  // PlayerTracker (via BrowserCdm) implementation.
+
+  int RegisterPlayer(const base::Closure& new_key_cb,
+                     const base::Closure& cdm_unset_cb) override;
+  void UnregisterPlayer(int registration_id) override;
+
+  // Accessor for MediaDrmBridge
+  MediaDrmBridge* GetDrmBridge();
+
+ private:
+  MediaDrmProxy(const std::string& key_system,
+                MediaDrmBridge::SecurityLevel widevine_security_level,
+                const SessionMessageCB& session_message_cb,
+                const SessionClosedCB& session_closed_cb,
+                const LegacySessionErrorCB& legacy_session_error_cb,
+                const SessionKeysChangeCB& session_keys_change_cb,
+                const SessionExpirationUpdateCB& session_expiration_update_cb);
+
+  // Helper method to create MediaDrmBridge on the Media thread.
+  void Initialize();
+
+  // Internal callbacks.
+  // We need to preserve the order of messages we send to the render process.
+  // Since we post the promise-related callbacks first from UI to Media thread
+  // and then back to UI thread, we need to do the same with session-related
+  // callbacks, too.
+  // We do this hopping with the promise-related callbacks to avoid a mutex in
+  // CdmPromiseAdapter, otherwise we could keep all callbacks on UI thread.
+
+  void OnSessionMessage(const std::string& session_id,
+                        MediaKeys::MessageType message_type,
+                        const std::vector<uint8>& message,
+                        const GURL& legacy_destination_url);
+  void OnSessionClosed(const std::string& session_id);
+  void OnLegacySessionError(const std::string& session_id,
+                            MediaKeys::Exception exception_code,
+                            uint32 system_code,
+                            const std::string& error_message);
+  void OnSessionKeysChange(const std::string& session_id,
+                           bool has_additional_usable_key,
+                           CdmKeysInfo keys_info);
+  void OnSessionExpirationUpdate(const std::string& session_id,
+                                 const base::Time& new_expiry_time);
+
+  // Data.
+
+  // Object for posting tasks on UI thread.
+  scoped_refptr<base::SingleThreadTaskRunner> ui_task_runner_;
+
+  // MediaDrmBridge that will be accessed on the Media thread.
+  scoped_ptr<MediaDrmBridge, BrowserCdmDeleter> media_drm_bridge_;
+
+  // The key system.
+  const std::string key_system_;
+
+  // Required security level. Only makes sense for Widevine system.
+  const MediaDrmBridge::SecurityLevel widevine_security_level_;
+
+  // Callbacks received as parameters, to be called on UI thread
+  SessionMessageCB session_message_cb_;
+  SessionClosedCB session_closed_cb_;
+  LegacySessionErrorCB legacy_session_error_cb_;
+  SessionKeysChangeCB session_keys_change_cb_;
+  SessionExpirationUpdateCB session_expiration_update_cb_;
+
+  // Internal callbacks passed to MediaDrmBridge, called on media thread.
+  SessionMessageCB internal_session_message_cb_;
+  SessionClosedCB internal_session_closed_cb_;
+  LegacySessionErrorCB internal_legacy_session_error_cb_;
+  SessionKeysChangeCB internal_session_keys_change_cb_;
+  SessionExpirationUpdateCB internal_session_expiration_update_cb_;
+
+  base::WeakPtr<MediaDrmProxy> media_weak_this_;
+
+  // NOTE: Weak pointers must be invalidated before all other member variables.
+  base::WeakPtrFactory<MediaDrmProxy> media_weak_factory_;
+
+  DISALLOW_COPY_AND_ASSIGN(MediaDrmProxy);
+};
+
+}  // namespace media
+
+#endif  // MEDIA_BASE_ANDROID_MEDIA_DRM_PROXY_H_