Implement setSinkId() for media elements without src.

third_party/WebKit/public/web/WebFrameClient.h

Index: third_party/WebKit/public/web/WebFrameClient.h
diff --git a/third_party/WebKit/public/web/WebFrameClient.h b/third_party/WebKit/public/web/WebFrameClient.h
index f1ccccc306f6b26595afec5557a5002c9e4bb5a8..fe84a47512db8374cb459984c4ad808d4f73ceb5 100644
--- a/third_party/WebKit/public/web/WebFrameClient.h
+++ b/third_party/WebKit/public/web/WebFrameClient.h
@@ -49,6 +49,7 @@
 #include "public/platform/WebFileSystem.h"
 #include "public/platform/WebFileSystemType.h"
 #include "public/platform/WebSecurityOrigin.h"
+#include "public/platform/WebSetSinkIdCallbacks.h"
 #include "public/platform/WebStorageQuotaCallbacks.h"
 #include "public/platform/WebStorageQuotaType.h"
 #include "public/platform/WebURLError.h"
@@ -680,6 +681,13 @@ public:
     // WebUSB --------------------------------------------------------------
     virtual WebUSBClient* usbClient() { return nullptr; }
 
+
+    // Audio Output Devices API --------------------------------------------
+
+    // Checks that the given audio sink exists and is authorized. The result is provided via the callbacks.
+    // This method takes ownership of the callbacks pointer.
+    virtual void checkIfAudioSinkExistsAndIsAuthorized(const WebString& sinkId, const WebSecurityOrigin&, WebSetSinkIdCallbacks*) { BLINK_ASSERT_NOT_REACHED(); }
+
 protected:
     virtual ~WebFrameClient() { }
 };