Sets a transparent background for out-of-process subframes.

android_webview/renderer/aw_render_frame_ext.h

Index: android_webview/renderer/aw_render_frame_ext.h
diff --git a/android_webview/renderer/aw_render_frame_ext.h b/android_webview/renderer/aw_render_frame_ext.h
index 804f281acb2d5362a738bb6e4db1f3b8a33c289b..09c9853ab58bfdea4facb9ae3b823d85b9d918d6 100644
--- a/android_webview/renderer/aw_render_frame_ext.h
+++ b/android_webview/renderer/aw_render_frame_ext.h
@@ -13,6 +13,7 @@
 
 namespace blink {
 enum WebMeaningfulLayout;
+class WebFrameWidget;
 class WebView;
 }
 
@@ -50,6 +51,7 @@ class AwRenderFrameExt : public content::RenderFrameObserver {
   void OnSmoothScroll(int target_x, int target_y, int duration_ms);
 
   blink::WebView* GetWebView();
+  blink::WebFrameWidget* GetWebFrameWidget();
 
   DISALLOW_COPY_AND_ASSIGN(AwRenderFrameExt);
 };