[Android WebView] Implement the capture picture API.

android_webview/browser/renderer_host/aw_render_view_host_ext.h

Index: android_webview/browser/renderer_host/aw_render_view_host_ext.h
diff --git a/android_webview/browser/renderer_host/aw_render_view_host_ext.h b/android_webview/browser/renderer_host/aw_render_view_host_ext.h
index 83bd439411ab2dbe2760ee7c3f76ea3f7a91d261..2f88ad8f132151335d3722b87f87595364d0d709 100644
--- a/android_webview/browser/renderer_host/aw_render_view_host_ext.h
+++ b/android_webview/browser/renderer_host/aw_render_view_host_ext.h
@@ -50,6 +50,14 @@ class AwRenderViewHostExt : public content::WebContentsObserver,
   // the corresponding public WebView API is as well.
   const AwHitTestData& GetLastHitTestData() const;
 
+  // Enables updating picture piles on every new frame.
+  // OnPictureUpdated is called when a new picture is available,
+  // stored by renderer id in RendererPictureMap.
+  void EnableCapturePictureCallback(bool enabled);
+
+  // Captures the latest available picture pile synchronously.
+  void CapturePictureSync();
+
  private:
   // content::WebContentsObserver implementation.
   virtual void RenderViewGone(base::TerminationStatus status) OVERRIDE;