navigation: Retain a screenshot of the page before it unloads

content/browser/web_contents/navigation_controller_impl.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.
 
 #ifndef CONTENT_BROWSER_WEB_CONTENTS_NAVIGATION_CONTROLLER_IMPL_H_
 #define CONTENT_BROWSER_WEB_CONTENTS_NAVIGATION_CONTROLLER_IMPL_H_
 
 #include "build/build_config.h"
 #include "base/callback.h"
 #include "base/compiler_specific.h"
 #include "base/gtest_prod_util.h"
 #include "base/memory/linked_ptr.h"
 #include "base/time.h"
 #include "content/browser/ssl/ssl_manager.h"
 #include "content/public/browser/navigation_controller.h"
 #include "content/public/browser/navigation_type.h"
 
 struct ViewHostMsg_FrameNavigate_Params;
 
+namespace skia {
+class PlatformBitmap;
+}
+
 namespace content {
 class NavigationEntryImpl;
 class WebContentsImpl;
 class SiteInstance;
 struct LoadCommittedDetails;
 
 class CONTENT_EXPORT NavigationControllerImpl
     : public NON_EXPORTED_BASE(NavigationController) {
  public:
   NavigationControllerImpl(
@@ skipping 271 matching lines @@
   // Inserts up to |max_index| entries from |source| into this. This does NOT
   // adjust any of the members that reference entries_
   // (last_committed_entry_index_, pending_entry_index_ or
   // transient_entry_index_).
   void InsertEntriesFrom(const NavigationControllerImpl& source, int max_index);
 
   // Returns the navigation index that differs from the current entry by the
   // specified |offset|.  The index returned is not guaranteed to be valid.
   int GetIndexForOffset(int offset) const;
 
+  // Takes a screenshot of the page at the current state.
+  void TakeScreenshot();
+
+  // The callback invoked when taking the screenshot of the page is complete.
+  // This sets the screenshot on the navigation entry.
+  void OnScreenshotTaken(int unique_id,
+                         skia::PlatformBitmap* bitmap,
+                         bool success);
+
   // ---------------------------------------------------------------------------
 
   // The user browser context associated with this controller.
   BrowserContext* browser_context_;
 
   // List of NavigationEntry for this tab
   typedef std::vector<linked_ptr<NavigationEntryImpl> > NavigationEntries;
   NavigationEntries entries_;
 
   // An entry we haven't gotten a response for yet.  This will be discarded
@@ skipping 63 matching lines @@
   // the timer resolution, leading to things sometimes showing up in
   // the wrong order in the history view.
   TimeSmoother time_smoother_;
 
   DISALLOW_COPY_AND_ASSIGN(NavigationControllerImpl);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_WEB_CONTENTS_NAVIGATION_CONTROLLER_IMPL_H_