gpu: Directly cast ClientBuffer to gfx::GpuMemoryBuffer

ui/aura/mus/mojo_gpu_memory_buffer_manager.cc

Index: ui/aura/mus/mojo_gpu_memory_buffer_manager.cc
diff --git a/ui/aura/mus/mojo_gpu_memory_buffer_manager.cc b/ui/aura/mus/mojo_gpu_memory_buffer_manager.cc
index 313d4d638b7e2c57e58f83b4afa91a2ac0954db6..ff5a7c7d305b0c95f84aab8e2d0b0303d29f1e2d 100644
--- a/ui/aura/mus/mojo_gpu_memory_buffer_manager.cc
+++ b/ui/aura/mus/mojo_gpu_memory_buffer_manager.cc
@@ -31,12 +31,6 @@ MojoGpuMemoryBufferManager::CreateGpuMemoryBufferFromHandle(
   return MojoGpuMemoryBufferImpl::CreateFromHandle(handle, size, format, usage);
 }
 
-gfx::GpuMemoryBuffer*
-MojoGpuMemoryBufferManager::GpuMemoryBufferFromClientBuffer(
-    ClientBuffer buffer) {
-  return MojoGpuMemoryBufferImpl::FromClientBuffer(buffer);
-}
-
 void MojoGpuMemoryBufferManager::SetDestructionSyncToken(
     gfx::GpuMemoryBuffer* buffer,
     const gpu::SyncToken& sync_token) {