Implement external stencil for Android WebView

android_webview/browser/parent_output_surface.h

 // Copyright 2014 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 ANDROID_WEBVIEW_BROWSER_PARENT_OUTPUT_SURFACE_H_
 #define ANDROID_WEBVIEW_BROWSER_PARENT_OUTPUT_SURFACE_H_
 
+#include "android_webview/browser/scoped_app_gl_state_restore.h"
 #include "base/macros.h"
 #include "cc/output/output_surface.h"
 
 namespace android_webview {
 
 class ParentOutputSurface : NON_EXPORTED_BASE(public cc::OutputSurface) {
  public:
   explicit ParentOutputSurface(
       scoped_refptr<cc::ContextProvider> context_provider);
   ~ParentOutputSurface() override;
 
   // OutputSurface overrides.
   void DidLoseOutputSurface() override;
   void Reshape(const gfx::Size& size,
                float scale_factor,
                bool has_alpha) override;
   void SwapBuffers(cc::CompositorFrame* frame) override;
-  using cc::OutputSurface::SetExternalStencilTest;
+  void ApplyExternalStencil() override;
+
+  void SetGLState(const ScopedAppGLStateRestore& gl_state);
 
  private:
+  StencilState stencil_state_;
+
   DISALLOW_COPY_AND_ASSIGN(ParentOutputSurface);
 };
 
 }  // namespace android_webview
 
 #endif  // ANDROID_WEBVIEW_BROWSER_PARENT_OUTPUT_SURFACE_H_