Disable low res tilings on desktop.

Stop creating low res tilings in the compositor on non-Android platforms.
The command line flags still exist to override this behaviour.

Android will continue to use low res tilings by default.

BUG=410610,407121

Review URL: https://codereview.chromium.org/536283002

Cr-Commit-Position: refs/heads/master@{#293858}

content/renderer/gpu/render_widget_compositor.cc

@@ -229,7 +229,6 @@ scoped_ptr<RenderWidgetCompositor> RenderWidgetCompositor::Create(
         render_thread->is_gpu_rasterization_forced();
     settings.gpu_rasterization_enabled =
         render_thread->is_gpu_rasterization_enabled();
-    settings.create_low_res_tiling = render_thread->is_low_res_tiling_enabled();
     settings.can_use_lcd_text = render_thread->is_lcd_text_enabled();
     settings.use_distance_field_text =
         render_thread->is_distance_field_text_enabled();
@@ -392,6 +391,9 @@ scoped_ptr<RenderWidgetCompositor> RenderWidgetCompositor::Create(
   settings.should_clear_root_render_pass =
       !synchronous_compositor_factory;
 
+  // TODO(danakj): Only do this on low end devices.
+  settings.create_low_res_tiling = true;
+
 #elif !defined(OS_MACOSX)
   if (ui::IsOverlayScrollbarEnabled()) {
     settings.scrollbar_animator = cc::LayerTreeSettings::Thinning;
@@ -407,6 +409,11 @@ scoped_ptr<RenderWidgetCompositor> RenderWidgetCompositor::Create(
   settings.scrollbar_fade_duration_ms = 300;
 #endif
 
+  if (cmd->HasSwitch(switches::kEnableLowResTiling))
+    settings.create_low_res_tiling = true;
+  if (cmd->HasSwitch(switches::kDisableLowResTiling))
+    settings.create_low_res_tiling = false;
+
   compositor->Initialize(settings);
 
   return compositor.Pass();

content/renderer/render_thread_impl.cc

@@ -511,12 +511,6 @@ void RenderThreadImpl::Init() {
     is_distance_field_text_enabled_ = false;
   }
 
-  is_low_res_tiling_enabled_ = true;
-  if (command_line.HasSwitch(switches::kDisableLowResTiling) &&
-      !command_line.HasSwitch(switches::kEnableLowResTiling)) {
-    is_low_res_tiling_enabled_ = false;
-  }
-
   // Note that under Linux, the media library will normally already have
   // been initialized by the Zygote before this instance became a Renderer.
   base::FilePath media_path;

content/renderer/render_thread_impl.h

@@ -223,8 +223,6 @@ class CONTENT_EXPORT RenderThreadImpl : public RenderThread,
     return is_impl_side_painting_enabled_;
   }
 
-  bool is_low_res_tiling_enabled() const { return is_low_res_tiling_enabled_; }
-
   bool is_lcd_text_enabled() const { return is_lcd_text_enabled_; }
 
   bool is_distance_field_text_enabled() const {
@@ -573,7 +571,6 @@ class CONTENT_EXPORT RenderThreadImpl : public RenderThread,
   bool is_gpu_rasterization_enabled_;
   bool is_gpu_rasterization_forced_;
   bool is_impl_side_painting_enabled_;
-  bool is_low_res_tiling_enabled_;
   bool is_lcd_text_enabled_;
   bool is_distance_field_text_enabled_;
   bool is_zero_copy_enabled_;