Extend components/test_runner's generated WebMediaStream to have a Chrome VideoTrack and Source

components/test_runner/web_test_delegate.h

Index: components/test_runner/web_test_delegate.h
diff --git a/components/test_runner/web_test_delegate.h b/components/test_runner/web_test_delegate.h
index 26b135a61c3b0fc9491ae8cd0691c26b3e54f374..d53852ec509b1c8603ba75c5b39899b209f9f934 100644
--- a/components/test_runner/web_test_delegate.h
+++ b/components/test_runner/web_test_delegate.h
@@ -27,13 +27,14 @@ class WebGamepads;
 class WebHistoryItem;
 class WebLayer;
 class WebLocalFrame;
+class WebMediaStream;
 class WebPlugin;
 struct WebPluginParams;
-class WebURLResponse;
-class WebView;
 struct WebRect;
 struct WebSize;
 struct WebURLError;
+class WebURLResponse;
+class WebView;
 }
 
 namespace cc {
@@ -244,6 +245,9 @@ class WebTestDelegate {
   // Clear all the permissions set via SetPermission().
   virtual void ResetPermissions() = 0;
 
+  // Add content MediaStream classes to the Blink MediaStream ones.
+  virtual bool AddMediaStreamSourceAndTrack(blink::WebMediaStream* stream) = 0;
+
   virtual cc::SharedBitmapManager* GetSharedBitmapManager() = 0;
 
   // Causes the beforeinstallprompt event to be sent to the renderer with a