Use observer pattern instead of sniffing SwapCompositorFrame IPC

content/browser/web_contents/web_contents_impl.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "content/browser/web_contents/web_contents_impl.h"
 
 #include <stddef.h>
 
 #include <cmath>
 #include <utility>
@@ skipping 5357 matching lines @@
     return;
   POINT cursor_pos = {};
   ::GetCursorPos(&cursor_pos);
   float scale = GetScaleFactorForView(view);
   gfx::Point location_dips_screen =
       gfx::ConvertPointToDIP(scale, gfx::Point(cursor_pos));
   view->FocusedNodeTouched(location_dips_screen, editable);
 #endif
 }
 
+void WebContentsImpl::DidReceiveCompositorFrame() {
+  for (auto& observer : observers_)
+    observer.DidReceiveCompositorFrame();
+}
+
 void WebContentsImpl::ShowInsecureLocalhostWarningIfNeeded() {
   bool allow_localhost = base::CommandLine::ForCurrentProcess()->HasSwitch(
       switches::kAllowInsecureLocalhost);
   if (!allow_localhost)
     return;
 
   content::NavigationEntry* entry = GetController().GetLastCommittedEntry();
   if (!entry || !net::IsLocalhost(entry->GetURL().host()))
     return;
 
@@ skipping 22 matching lines @@
     RenderViewHost* render_view_host = RenderViewHost::From(render_widget_host);
     if (!render_view_host)
       continue;
     render_view_host_set.insert(render_view_host);
   }
   for (RenderViewHost* render_view_host : render_view_host_set)
     render_view_host->OnWebkitPreferencesChanged();
 }
 
 }  // namespace content