Add an IPC to return the platform supported key-system names in Android.

media/base/android/media_drm_bridge.h

 // Copyright (c) 2013 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_BRIDGE_H_
 #define MEDIA_BASE_ANDROID_MEDIA_DRM_BRIDGE_H_
 
 #include <jni.h>
 #include <string>
 #include <vector>
@@ skipping 30 matching lines @@
   // All other static methods check IsAvailable() internally. There's no need
   // to check IsAvailable() explicitly before calling them.
   static bool IsAvailable();
 
   static bool IsSecurityLevelSupported(const std::string& key_system,
                                        SecurityLevel security_level);
 
   // Checks whether |key_system| is supported.
   static bool IsKeySystemSupported(const std::string& key_system);
 
+  // Returns the list of the key system names that platform supports besides
+  // WideVine.

[ddorwin, 2014/06/11 01:54:02]

Small 'V'.

However, it might be better to explain what this list is instead of calling out
specific key system(s). See my earlier comment.

[ycheo (away), 2014/06/11 07:43:43]

Done.

+  static std::vector<std::string> GetPlatformKeySystemNames();
+
   // Adds a new |key_system| with the associated |uuid|.
   // This is used for other platforms to have a chance to register their
   // own UUID mapping.
   static void AddKeySystemUuidMapping(const std::string& key_system,
                                       const std::vector<uint8>& uuid);
 
   // Checks whether |key_system| is supported with |container_mime_type|.
   // |container_mime_type| must not be empty.
   static bool IsKeySystemSupportedWithType(
       const std::string& key_system,
@@ skipping 107 matching lines @@
   ResetCredentialsCB reset_credentials_cb_;
 
   PlayerTrackerImpl player_tracker_;
 
   DISALLOW_COPY_AND_ASSIGN(MediaDrmBridge);
 };
 
 }  // namespace media
 
 #endif  // MEDIA_BASE_ANDROID_MEDIA_DRM_BRIDGE_H_