Re-land: cc: Use worker context for one-copy tile initialization.

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>
 
 #include "base/command_line.h"
@@ skipping 452 matching lines @@
     settings.create_low_res_tiling = false;
   if (cmd->HasSwitch(cc::switches::kEnableBeginFrameScheduling))
     settings.use_external_begin_frame_source = true;
 
   if (widget_->for_oopif()) {
     // TODO(simonhong): Apply BeginFrame scheduling for OOPIF.
     // See crbug.com/471411.
     settings.use_external_begin_frame_source = false;
   }
 
+  settings.max_staging_buffers = 32;
+  // Use 1/4th of staging buffers on low-end devices.
+  if (base::SysInfo::IsLowEndDevice())
+    settings.max_staging_buffers /= 4;
+
   scoped_refptr<base::SingleThreadTaskRunner> compositor_thread_task_runner =
       compositor_deps_->GetCompositorImplThreadTaskRunner();
   scoped_refptr<base::SingleThreadTaskRunner>
       main_thread_compositor_task_runner =
           compositor_deps_->GetCompositorMainThreadTaskRunner();
   cc::SharedBitmapManager* shared_bitmap_manager =
       compositor_deps_->GetSharedBitmapManager();
   gpu::GpuMemoryBufferManager* gpu_memory_buffer_manager =
       compositor_deps_->GetGpuMemoryBufferManager();
   cc::TaskGraphRunner* task_graph_runner =
@@ skipping 562 matching lines @@
     return;
   provider->ContextGL()->RateLimitOffscreenContextCHROMIUM();
 }
 
 void RenderWidgetCompositor::SetSurfaceIdNamespace(
     uint32_t surface_id_namespace) {
   layer_tree_host_->set_surface_id_namespace(surface_id_namespace);
 }
 
 }  // namespace content