gpu: Add GpuFence framework.

blimp/client/support/compositor/blimp_gpu_memory_buffer_manager.h

Index: blimp/client/support/compositor/blimp_gpu_memory_buffer_manager.h
diff --git a/blimp/client/support/compositor/blimp_gpu_memory_buffer_manager.h b/blimp/client/support/compositor/blimp_gpu_memory_buffer_manager.h
index e0501af492032984b3dfc7751364f5184ae25963..6c51dbec582b5f68897d9af8cd55925762532330 100644
--- a/blimp/client/support/compositor/blimp_gpu_memory_buffer_manager.h
+++ b/blimp/client/support/compositor/blimp_gpu_memory_buffer_manager.h
@@ -33,6 +33,10 @@ class BlimpGpuMemoryBufferManager : public gpu::GpuMemoryBufferManager {
       gfx::BufferFormat format) override;
   void SetDestructionSyncToken(gfx::GpuMemoryBuffer* buffer,
                                const gpu::SyncToken& sync_token) override;
+  std::unique_ptr<gfx::GpuFence> CreateGpuFence() override;
+  std::unique_ptr<gfx::GpuFence> CreateGpuFenceFromHandle(
+      const gfx::GpuFenceHandle& handle) override;
+  gfx::GpuFence* GpuFenceFromClientFence(ClientFence fence) override;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(BlimpGpuMemoryBufferManager);