Make cc::SurfaceId unguessable

content/browser/browser_plugin/browser_plugin_guest.h

 // 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.
 
 // A BrowserPluginGuest is the browser side of a browser <--> embedder
 // renderer channel. A BrowserPlugin (a WebPlugin) is on the embedder
 // renderer side of browser <--> embedder renderer communication.
 //
 // BrowserPluginGuest lives on the UI thread of the browser process. Any
 // messages about the guest render process that the embedder might be interested
@@ skipping 34 matching lines @@
 #include "ui/gfx/geometry/rect.h"
 
 struct BrowserPluginHostMsg_Attach_Params;
 
 #if defined(OS_MACOSX)
 struct FrameHostMsg_ShowPopup_Params;
 #endif
 
 namespace cc {
 class CompositorFrame;
-struct SurfaceId;
+class SurfaceId;
 struct SurfaceSequence;
 }  // namespace cc
 
 namespace gfx {
 class Range;
 }  // namespace gfx
 
 namespace content {
 
 class BrowserPluginGuestManager;
@@ skipping 383 matching lines @@
   // Weak pointer used to ask GeolocationPermissionContext about geolocation
   // permission.
   base::WeakPtrFactory<BrowserPluginGuest> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(BrowserPluginGuest);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_BROWSER_PLUGIN_BROWSER_PLUGIN_GUEST_H_