MediaStream API: Addding support for UA specific error messages for gUM

public/web/WebUserMediaRequest.h

Index: public/web/WebUserMediaRequest.h
diff --git a/public/web/WebUserMediaRequest.h b/public/web/WebUserMediaRequest.h
index 562e77b09d1fed09a7b8db49f44303c593a0a5a8..50f1745309cd8a0eab25769714dd17d364ac46fd 100644
--- a/public/web/WebUserMediaRequest.h
+++ b/public/web/WebUserMediaRequest.h
@@ -74,8 +74,12 @@ public:
 
     BLINK_EXPORT void requestSucceeded(const WebMediaStream&);
 
-    BLINK_EXPORT void requestFailed(const WebString& description = WebString());
+    BLINK_EXPORT void requestDenied(const WebString& description = WebString());
     BLINK_EXPORT void requestFailedConstraint(const WebString& constraintName, const WebString& description = WebString());
+    BLINK_EXPORT void requestFailedUASpecific(const WebString& name, const WebString& constraintName = WebString(), const WebString& description = WebString());
+
+    // DEPRECATED
+    BLINK_EXPORT void requestFailed(const WebString& description = WebString()) { requestDenied(description); }
 
 #if BLINK_IMPLEMENTATION
     WebUserMediaRequest(const PassRefPtr<WebCore::UserMediaRequest>&);