gpu: Directly cast ClientBuffer to gfx::GpuMemoryBuffer

gpu/ipc/client/gpu_memory_buffer_impl.cc

Index: gpu/ipc/client/gpu_memory_buffer_impl.cc
diff --git a/gpu/ipc/client/gpu_memory_buffer_impl.cc b/gpu/ipc/client/gpu_memory_buffer_impl.cc
index 5327088a0543745780bdaca5657a09c983296b4f..185e921f78ab886719608f450aa4da3a087002a0 100644
--- a/gpu/ipc/client/gpu_memory_buffer_impl.cc
+++ b/gpu/ipc/client/gpu_memory_buffer_impl.cc
@@ -60,12 +60,6 @@ std::unique_ptr<GpuMemoryBufferImpl> GpuMemoryBufferImpl::CreateFromHandle(
   }
 }
 
-// static
-GpuMemoryBufferImpl* GpuMemoryBufferImpl::FromClientBuffer(
-    ClientBuffer buffer) {
-  return reinterpret_cast<GpuMemoryBufferImpl*>(buffer);
-}
-
 gfx::Size GpuMemoryBufferImpl::GetSize() const {
   return size_;
 }