[NotLanded] Implement the fetching algorithm of the Web Manifest.

Source/web/FrameLoaderClientImpl.h

Index: Source/web/FrameLoaderClientImpl.h
diff --git a/Source/web/FrameLoaderClientImpl.h b/Source/web/FrameLoaderClientImpl.h
index afe7014f79e29a11d2fff77d027ba4d606f78311..e9bee2ac46309120a0da0810bef0f70a3ce191b4 100644
--- a/Source/web/FrameLoaderClientImpl.h
+++ b/Source/web/FrameLoaderClientImpl.h
@@ -165,6 +165,8 @@ public:
     virtual void didStopAllLoaders() OVERRIDE;
 
     virtual void dispatchDidChangeManifest() OVERRIDE;
+    virtual void dispatchDidLoadManifest(WebManifest) OVERRIDE;
+    virtual void dispatchDidFailLoadManifest(WebManifestError) OVERRIDE;
 
 private:
     virtual bool isFrameLoaderClientImpl() const OVERRIDE { return true; }