Do not clear root frame buffer for android webview

content/renderer/gpu/render_widget_compositor.cc

 // Copyright (c) 2013 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.
 
 #include "content/renderer/gpu/render_widget_compositor.h"
 
 #include <limits>
 #include <string>
 
 #if defined(OS_ANDROID)
@@ skipping 261 matching lines @@
     // On low-end we want to be very carefull about killing other
     // apps. So initially we use 50% more memory to avoid flickering
     // or raster-on-demand.
     settings.max_memory_for_prepaint_percentage = 67;
   } else {
     // On other devices we have increased memory excessively to avoid
     // raster-on-demand already, so now we reserve 50% _only_ to avoid
     // raster-on-demand, and use 50% of the memory otherwise.
     settings.max_memory_for_prepaint_percentage = 50;
   }
+  // Webview does not own the surface so should not clear it.
+  settings.should_clear_root_render_pass =
+      !widget->UsingSynchronousRendererCompositor();
 
 #elif !defined(OS_MACOSX)
   if (ui::IsOverlayScrollbarEnabled()) {
     settings.scrollbar_animator = cc::LayerTreeSettings::Thinning;
     settings.solid_color_scrollbar_color = SkColorSetARGB(128, 128, 128, 128);
   } else if (cmd->HasSwitch(cc::switches::kEnablePinchVirtualViewport)) {
     settings.scrollbar_animator = cc::LayerTreeSettings::LinearFade;
     settings.solid_color_scrollbar_color = SkColorSetARGB(128, 128, 128, 128);
   }
 #endif
@@ skipping 354 matching lines @@
   widget_->OnSwapBuffersAborted();
 }
 
 void RenderWidgetCompositor::RateLimitSharedMainThreadContext() {
   cc::ContextProvider* provider =
       RenderThreadImpl::current()->SharedMainThreadContextProvider().get();
   provider->ContextGL()->RateLimitOffscreenContextCHROMIUM();
 }
 
 }  // namespace content