gpu: Add flag for enabling asynchronous worker context.

content/renderer/renderer_blink_platform_impl.cc

Index: content/renderer/renderer_blink_platform_impl.cc
diff --git a/content/renderer/renderer_blink_platform_impl.cc b/content/renderer/renderer_blink_platform_impl.cc
index d9c1890086be640f29f8347b494e9b3315742619..8e1d03fdccea90ddeb8bc0aa5adc9a5c2dc59ae6 100644
--- a/content/renderer/renderer_blink_platform_impl.cc
+++ b/content/renderer/renderer_blink_platform_impl.cc
@@ -78,6 +78,7 @@
 #include "gpu/command_buffer/client/gles2_interface.h"
 #include "gpu/config/gpu_info.h"
 #include "gpu/ipc/client/gpu_channel_host.h"
+#include "gpu/ipc/common/gpu_stream_constants.h"
 #include "ipc/ipc_sync_message_filter.h"
 #include "media/audio/audio_output_device.h"
 #include "media/base/audio_hardware_config.h"
@@ -1077,7 +1078,8 @@ RendererBlinkPlatformImpl::createOffscreenGraphicsContext3DProvider(
       new ContextProviderCommandBuffer(
           base::WrapUnique(new WebGraphicsContext3DCommandBufferImpl(
               gpu::kNullSurfaceHandle, GURL(top_document_web_url),
-              std::move(gpu_channel_host), gpu_preference, automatic_flushes)),
+              std::move(gpu_channel_host), gpu_preference, automatic_flushes,
+              gpu::GPU_STREAM_DEFAULT, gpu::GpuStreamPriority::NORMAL)),
           gpu::SharedMemoryLimits(), attributes, share_context,
           command_buffer_metrics::OFFSCREEN_CONTEXT_FOR_WEBGL));
   if (!provider->BindToCurrentThread()) {