Remove implicit conversions from scoped_refptr to T* in gpu/

gpu/command_buffer/client/mapped_memory.cc

Index: gpu/command_buffer/client/mapped_memory.cc
diff --git a/gpu/command_buffer/client/mapped_memory.cc b/gpu/command_buffer/client/mapped_memory.cc
index 7166733c51c6239acc49dd3319b4aaa2186168be..fc6ca5dad9aff8be1713a1ff4f9cb8e48a268784 100644
--- a/gpu/command_buffer/client/mapped_memory.cc
+++ b/gpu/command_buffer/client/mapped_memory.cc
@@ -91,7 +91,7 @@ void* MappedMemoryManager::Alloc(
       cmd_buf->CreateTransferBuffer(chunk_size, &id);
   if (id  < 0)
     return NULL;
-  DCHECK(shm);
+  DCHECK(shm.get());
   MemoryChunk* mc = new MemoryChunk(id, shm, helper_, poll_callback_);
   allocated_memory_ += mc->GetSize();
   chunks_.push_back(mc);