Expose locks for CopyFromCompositingSurface/CopyFromBackingStore API

content/public/browser/render_widget_host.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_PUBLIC_BROWSER_RENDER_WIDGET_HOST_H_
 #define CONTENT_PUBLIC_BROWSER_RENDER_WIDGET_HOST_H_
 
 #include "base/callback.h"
 #include "content/common/content_export.h"
 #include "content/public/browser/native_web_keyboard_event.h"
@@ skipping 182 matching lines @@
   // source contents is used. |callback| is invoked with true on success, false
   // otherwise, along with a SkBitmap containing the copied pixel data.
   //
   // NOTE: |callback| is called synchronously if the backing store is available.
   // When accelerated compositing is active, |callback| may be called
   // asynchronously.
   virtual void CopyFromBackingStore(
       const gfx::Rect& src_rect,
       const gfx::Size& accelerated_dst_size,
       const base::Callback<void(bool, const SkBitmap&)>& callback) = 0;
+  // Ensures that the view does not drop the backing store even when hidden.

[jam, 2014/02/26 22:57:52]

perhaps these methods should be in an OS_ANDROID ifdef since they're only
implemented on that platform?

[powei, 2014/03/03 09:20:54]

Done.

+  virtual bool CanCopyFromBackingStore() = 0;
+  virtual void LockForCopyFromBackingStore() = 0;
+  virtual void UnlockForCopyFromBackingStore() = 0;
 #if defined(TOOLKIT_GTK)
   // Paint the backing store into the target's |dest_rect|.
   virtual bool CopyFromBackingStoreToGtkWindow(const gfx::Rect& dest_rect,
                                                GdkWindow* target) = 0;
 #elif defined(OS_MACOSX)
   virtual gfx::Size GetBackingStoreSize() = 0;
   virtual bool CopyFromBackingStoreToCGContext(const CGRect& dest_rect,
                                                CGContextRef target) = 0;
 #endif
 
@@ skipping 90 matching lines @@
   // within content/.  This method is necessary because
   // RenderWidgetHost is the root of a diamond inheritance pattern, so
   // subclasses inherit it virtually, which removes our ability to
   // static_cast to the subclass.
   virtual RenderWidgetHostImpl* AsRenderWidgetHostImpl() = 0;
 };
 
 }  // namespace content
 
 #endif  // CONTENT_PUBLIC_BROWSER_RENDER_WIDGET_HOST_H_