Update from https://crrev.com/304418

gpu/command_buffer/client/mapped_memory.cc

 // Copyright (c) 2011 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "gpu/command_buffer/client/mapped_memory.h"
 
 #include <algorithm>
 #include <functional>
 
 #include "base/debug/trace_event.h"
 #include "base/logging.h"
 #include "gpu/command_buffer/client/cmd_buffer_helper.h"
 
 namespace gpu {
 
 MemoryChunk::MemoryChunk(int32 shm_id,
                          scoped_refptr<gpu::Buffer> shm,
                          CommandBufferHelper* helper,
                          const base::Closure& poll_callback)
     : shm_id_(shm_id),
       shm_(shm),
       allocator_(shm->size(), helper, poll_callback, shm->memory()) {}
 
 MemoryChunk::~MemoryChunk() {}
 
 MappedMemoryManager::MappedMemoryManager(CommandBufferHelper* helper,
                                          const base::Closure& poll_callback,
                                          size_t unused_memory_reclaim_limit)
-    : chunk_size_multiple_(1),
+    : chunk_size_multiple_(FencedAllocator::kAllocAlignment),
       helper_(helper),
       poll_callback_(poll_callback),
       allocated_memory_(0),
       max_free_bytes_(unused_memory_reclaim_limit) {
 }
 
 MappedMemoryManager::~MappedMemoryManager() {
   CommandBuffer* cmd_buf = helper_->command_buffer();
   for (MemoryChunkVector::iterator iter = chunks_.begin();
        iter != chunks_.end(); ++iter) {
@@ skipping 94 matching lines @@
       cmd_buf->DestroyTransferBuffer(chunk->shm_id());
       allocated_memory_ -= chunk->GetSize();
       iter = chunks_.erase(iter);
     } else {
       ++iter;
     }
   }
 }
 
 }  // namespace gpu