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

media/base/android/media_drm_bridge.h

Index: media/base/android/media_drm_bridge.h
diff --git a/media/base/android/media_drm_bridge.h b/media/base/android/media_drm_bridge.h
index a7a28bd3b627e0e4bfa74f5e5f0c1cfa985ac835..9c5fceba25b7a1adb441d046a6588fd122745536 100644
--- a/media/base/android/media_drm_bridge.h
+++ b/media/base/android/media_drm_bridge.h
@@ -48,6 +48,10 @@ class MEDIA_EXPORT MediaDrmBridge : public BrowserCdm {
   // 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.