gpu: Use mojom API for creating gpu channel.

content/gpu/gpu_child_thread.h

Index: content/gpu/gpu_child_thread.h
diff --git a/content/gpu/gpu_child_thread.h b/content/gpu/gpu_child_thread.h
index c8b7724e55570ffd932ad568dcf830bd8ea8702a..f1dc4e92cc1d038ecec8372382ca7bafdbb720de 100644
--- a/content/gpu/gpu_child_thread.h
+++ b/content/gpu/gpu_child_thread.h
@@ -46,7 +46,6 @@ class TargetServices;
 
 namespace content {
 class GpuServiceFactory;
-struct EstablishChannelParams;
 
 // The main thread of the GPU child process. There will only ever be one of
 // these per process. It does process initialization and shutdown. It forwards
@@ -124,7 +123,6 @@ class GpuChildThread : public ChildThreadImpl,
 #endif
   void OnGpuSwitched();
 
-  void OnEstablishChannel(const EstablishChannelParams& params);
   void OnCloseChannel(int32_t client_id);
   void OnLoadedShader(const std::string& shader);
   void OnDestroyGpuMemoryBuffer(gfx::GpuMemoryBufferId id,