Report manifest URL changes to WebContentsObservers.

Bug: 707179
Change-Id: I57c859d27c7f940002cceb2923e6418a75acb92a
Reviewed-on: https://chromium-review.googlesource.com/497233
Commit-Queue: Sam McNally <[email protected]>
Reviewed-by: Nasko Oskov <[email protected]>
Cr-Commit-Position: refs/heads/master@{#470796}
diff --git a/content/public/browser/web_contents_observer.h b/content/public/browser/web_contents_observer.h
index 92b3f53..f29957bd 100644
--- a/content/public/browser/web_contents_observer.h
+++ b/content/public/browser/web_contents_observer.h
@@ -426,6 +426,15 @@
   // Notifes that a CompositorFrame was received from the renderer.
   virtual void DidReceiveCompositorFrame() {}
 
+  // Notifies that the manifest URL for the main frame changed to
+  // |manifest_url|. This will be invoked when a document with a manifest loads
+  // or when the manifest URL changes (possibly to nothing). It is not invoked
+  // when a document with no manifest loads. During document load, if the
+  // document has both a manifest and a favicon, DidUpdateWebManifestURL() will
+  // be invoked before DidUpdateFaviconURL().
+  virtual void DidUpdateWebManifestURL(
+      const base::Optional<GURL>& manifest_url) {}
+
   // IPC::Listener implementation.
   bool OnMessageReceived(const IPC::Message& message) override;