gpu: Add flag for enabling asynchronous worker context.

content/renderer/render_widget.cc

 // Copyright (c) 2012 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/render_widget.h"
 
 #include <memory>
 #include <utility>
 
 #include "base/auto_reset.h"
@@ skipping 757 matching lines @@
     attributes.alpha_size = -1;
     attributes.depth_size = 0;
     attributes.stencil_size = 0;
     attributes.samples = 0;
     attributes.sample_buffers = 0;
     attributes.bind_generates_resource = false;
     attributes.lose_context_when_out_of_memory = true;
 
     bool automatic_flushes = false;
 
-    // The compositor context shares resources with the worker context.
+    // The compositor context shares resources with the worker context unless
+    // the worker is async.
+    ContextProviderCommandBuffer* share_context = worker_context_provider.get();
+    if (base::CommandLine::ForCurrentProcess()->HasSwitch(
+            switches::kEnableGpuAsyncWorkerContext)) {
+      share_context = nullptr;
+    }
     context_provider = new ContextProviderCommandBuffer(
         base::WrapUnique(new content::WebGraphicsContext3DCommandBufferImpl(
             gpu::kNullSurfaceHandle, GetURLForGraphicsContext3D(),
             std::move(gpu_channel_host), gfx::PreferIntegratedGpu,
-            automatic_flushes)),
+            automatic_flushes, gpu::GPU_STREAM_DEFAULT,
+            gpu::GpuStreamPriority::NORMAL)),
         limits, attributes, worker_context_provider.get(),
         command_buffer_metrics::RENDER_COMPOSITOR_CONTEXT);
 
 #if defined(OS_ANDROID)
     if (RenderThreadImpl::current() &&
         RenderThreadImpl::current()->sync_compositor_message_filter()) {
       uint32_t output_surface_id = next_output_surface_id_++;
       return base::WrapUnique(new SynchronousCompositorOutputSurface(
           context_provider, worker_context_provider, routing_id(),
           output_surface_id,
@@ skipping 1302 matching lines @@
 }
 
 float RenderWidget::GetOriginalDeviceScaleFactor() const {
   return
       screen_metrics_emulator_ ?
       screen_metrics_emulator_->original_screen_info().deviceScaleFactor :
       device_scale_factor_;
 }
 
 }  // namespace content