Add MediaError.message

third_party/WebKit/public/platform/WebMediaPlayer.h

Index: third_party/WebKit/public/platform/WebMediaPlayer.h
diff --git a/third_party/WebKit/public/platform/WebMediaPlayer.h b/third_party/WebKit/public/platform/WebMediaPlayer.h
index 4f17e2e0172cee478408227f14c4209c80e7557d..a637b93b8edb4361265c54d995d23b5cb8313a49 100644
--- a/third_party/WebKit/public/platform/WebMediaPlayer.h
+++ b/third_party/WebKit/public/platform/WebMediaPlayer.h
@@ -159,7 +159,12 @@ class WebMediaPlayer {
   virtual NetworkState GetNetworkState() const = 0;
   virtual ReadyState GetReadyState() const = 0;
 
-  virtual WebString GetErrorMessage() = 0;
+  // Returns an implementation-specific human readable error message, or an
+  // empty string if no message is available. The message should begin with a
+  // UA-specific-error-code (without any ':'), optionally followed by ': ' and
+  // further description of the error.
+  virtual WebString GetErrorMessage() const = 0;
+
   virtual bool DidLoadingProgress() = 0;
 
   virtual bool HasSingleSecurityOrigin() const = 0;