Use hide_scrollbars setting 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 <stddef.h>
 #include <limits>
 #include <string>
 #include <utility>
@@ skipping 366 matching lines @@
 
 #if defined(OS_ANDROID)
   bool using_synchronous_compositor =
       GetContentClient()->UsingSynchronousCompositing();
 
   // We can't use GPU rasterization on low-end devices, because the Ganesh
   // cache would consume too much memory.
   if (base::SysInfo::IsLowEndDevice())
     settings.gpu_rasterization_enabled = false;
   settings.using_synchronous_renderer_compositor = using_synchronous_compositor;
-  if (using_synchronous_compositor) {
-    // Android WebView uses system scrollbars, so make ours invisible.
-    settings.scrollbar_animator = cc::LayerTreeSettings::NO_ANIMATOR;
-    settings.solid_color_scrollbar_color = SK_ColorTRANSPARENT;
-  } else {
-    settings.scrollbar_animator = cc::LayerTreeSettings::LINEAR_FADE;
-    settings.scrollbar_fade_delay_ms = 300;
-    settings.scrollbar_fade_resize_delay_ms = 2000;
-    settings.scrollbar_fade_duration_ms = 300;
-    settings.solid_color_scrollbar_color = SkColorSetARGB(128, 128, 128, 128);
-  }
+  settings.scrollbar_animator = cc::LayerTreeSettings::LINEAR_FADE;
+  settings.scrollbar_fade_delay_ms = 300;
+  settings.scrollbar_fade_resize_delay_ms = 2000;
+  settings.scrollbar_fade_duration_ms = 300;
+  settings.solid_color_scrollbar_color = SkColorSetARGB(128, 128, 128, 128);
   settings.renderer_settings.highp_threshold_min = 2048;
   // Android WebView handles root layer flings itself.
   settings.ignore_root_layer_flings = using_synchronous_compositor;
   // Memory policy on Android WebView does not depend on whether device is
   // low end, so always use default policy.
   bool use_low_memory_policy =
       base::SysInfo::IsLowEndDevice() && !using_synchronous_compositor;
   if (use_low_memory_policy) {
     // On low-end we want to be very carefull about killing other
     // apps. So initially we use 50% more memory to avoid flickering
@@ skipping 712 matching lines @@
     float device_scale) {
   layer_tree_host_->GetLayerTree()->SetPaintedDeviceScaleFactor(device_scale);
 }
 
 void RenderWidgetCompositor::SetDeviceColorSpace(
     const gfx::ColorSpace& color_space) {
   layer_tree_host_->GetLayerTree()->SetDeviceColorSpace(color_space);
 }
 
 }  // namespace content