Make FencedAlloctor fail on size = 0.

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 <algorithm>
 #include <functional>
 
 #include "../client/mapped_memory.h"
 #include "../client/cmd_buffer_helper.h"
 
@@ skipping 36 matching lines @@
       GPU_DCHECK(mem);
       *shm_id = chunk->shm_id();
       *shm_offset = chunk->GetOffset(mem);
       return mem;
     }
   }
 
   // Make a new chunk to satisfy the request.
   CommandBuffer* cmd_buf = helper_->command_buffer();
   unsigned int chunk_size =
-      ((size + chunk_size_multiple_ - 1) / chunk_size_multiple_) *
+      ((std::max(1u, size) + chunk_size_multiple_ - 1) / chunk_size_multiple_) *
       chunk_size_multiple_;
   int32 id = cmd_buf->CreateTransferBuffer(chunk_size, -1);
   if (id == -1) {
     return NULL;
   }
   gpu::Buffer shm = cmd_buf->GetTransferBuffer(id);
   MemoryChunk* mc = new MemoryChunk(id, shm, helper_);
   chunks_.push_back(mc);
   void* mem = mc->Alloc(size);
   GPU_DCHECK(mem);
@@ skipping 36 matching lines @@
     } else {
       ++iter;
     }
   }
 }
 
 }  // namespace gpu