Query the preferred readback config in CopyFromBackingStore

content/public/browser/render_widget_host.h

Index: content/public/browser/render_widget_host.h
diff --git a/content/public/browser/render_widget_host.h b/content/public/browser/render_widget_host.h
index fbddb79aa0aeab17036a6498bbd6f5015db2cec5..c9fd677f7f088e39a31c90d6dad7b48828c2f59d 100644
--- a/content/public/browser/render_widget_host.h
+++ b/content/public/browser/render_widget_host.h
@@ -10,6 +10,7 @@
 #include "content/public/browser/native_web_keyboard_event.h"
 #include "ipc/ipc_channel.h"
 #include "ipc/ipc_sender.h"
+#include "third_party/skia/include/core/SkBitmap.h"
 #include "third_party/WebKit/public/web/WebInputEvent.h"
 #include "third_party/WebKit/public/web/WebTextDirection.h"
 #include "ui/gfx/size.h"
@@ -197,7 +198,8 @@ class CONTENT_EXPORT RenderWidgetHost : public IPC::Sender {
   virtual void CopyFromBackingStore(
       const gfx::Rect& src_rect,
       const gfx::Size& accelerated_dst_size,
-      const base::Callback<void(bool, const SkBitmap&)>& callback) = 0;
+      const base::Callback<void(bool, const SkBitmap&)>& callback,
+      const SkBitmap::Config& bitmap_config) = 0;
 #if defined(TOOLKIT_GTK)
   // Paint the backing store into the target's |dest_rect|.
   virtual bool CopyFromBackingStoreToGtkWindow(const gfx::Rect& dest_rect,
@@ -294,6 +296,8 @@ class CONTENT_EXPORT RenderWidgetHost : public IPC::Sender {
       const gfx::Rect& src_subrect,
       const base::Callback<void(bool, const SkBitmap&)>& callback) = 0;
 
+  virtual SkBitmap::Config PreferredReadbackFormat() = 0;
+
  protected:
   friend class RenderWidgetHostImpl;