Implement offscreenCanvas.getContext('webgl') on a worker thread

gpu/ipc/client/command_buffer_proxy_impl.h

 // 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.
 
 #ifndef GPU_IPC_CLIENT_COMMAND_BUFFER_PROXY_IMPL_H_
 #define GPU_IPC_CLIENT_COMMAND_BUFFER_PROXY_IMPL_H_
 
 #include <stddef.h>
 #include <stdint.h>
 
@@ skipping 84 matching lines @@
                       size_t width,
                       size_t height,
                       unsigned internal_format) override;
   void DestroyImage(int32_t id) override;
   int32_t CreateGpuMemoryBufferImage(size_t width,
                                      size_t height,
                                      unsigned internal_format,
                                      unsigned usage) override;
   void SignalQuery(uint32_t query, const base::Closure& callback) override;
   void SetLock(base::Lock* lock) override;
+  void DetachFromThread() { lockless_thread_checker_.DetachFromThread(); }
   void EnsureWorkVisible() override;
   gpu::CommandBufferNamespace GetNamespaceID() const override;
   gpu::CommandBufferId GetCommandBufferID() const override;
   int32_t GetExtraCommandBufferData() const override;
   uint64_t GenerateFenceSyncRelease() override;
   bool IsFenceSyncRelease(uint64_t release) override;
   bool IsFenceSyncFlushed(uint64_t release) override;
   bool IsFenceSyncFlushReceived(uint64_t release) override;
   void SignalSyncToken(const gpu::SyncToken& sync_token,
                        const base::Closure& callback) override;
@@ skipping 152 matching lines @@
 
   base::WeakPtr<CommandBufferProxyImpl> weak_this_;
   scoped_refptr<base::SequencedTaskRunner> callback_thread_;
 
   DISALLOW_COPY_AND_ASSIGN(CommandBufferProxyImpl);
 };
 
 }  // namespace gpu
 
 #endif  // GPU_IPC_CLIENT_COMMAND_BUFFER_PROXY_IMPL_H_