chrome: Cleanup class/struct forward declarations

chrome/browser/android/offline_pages/prerendering_loader.h

 // Copyright 2016 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.
 
 #ifndef CHROME_BROWSER_ANDROID_OFFLINE_PAGES_PRERENDERING_LOADER_H_
 #define CHROME_BROWSER_ANDROID_OFFLINE_PAGES_PRERENDERING_LOADER_H_
 
 #include <memory>
 
 #include "base/callback.h"
 #include "chrome/browser/android/offline_pages/prerender_adapter.h"
 #include "components/offline_pages/background/offliner.h"
 #include "components/offline_pages/snapshot_controller.h"
 
 class GURL;
 
 namespace content {
 class BrowserContext;
 class WebContents;
-class SessionStorageNamespace;
 }  // namespace content
 
-namespace gfx {
-class Size;
-}  // namespace gfx
-
 namespace offline_pages {
 
 // A client-side page loader that integrates with the PrerenderManager to do
 // the page loading in the background. It operates on a single thread and
 // needs to run on BrowserThread::UI to work with the PrerenderManager.
 // It supports a single load request at a time.
 class PrerenderingLoader : public PrerenderAdapter::Observer,
                            public SnapshotController::Client {
  public:
   // Reports status of a load page request with loaded contents if available.
@@ skipping 87 matching lines @@
   // Callback to call when the active load request completes, fails, or is
   // canceled.
   LoadPageCallback callback_;
 
   DISALLOW_COPY_AND_ASSIGN(PrerenderingLoader);
 };
 
 }  // namespace offline_pages
 
 #endif  // CHROME_BROWSER_ANDROID_OFFLINE_PAGES_PRERENDERING_LOADER_H_