Add GenericSharedMemoryId and use w/ GpuMemoryBuffer

cc/test/test_gpu_memory_buffer_manager.cc

 // Copyright 2014 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 "cc/test/test_gpu_memory_buffer_manager.h"
 
 #include "base/logging.h"
 #include "base/numerics/safe_conversions.h"
 #include "ui/gfx/buffer_format_util.h"
 #include "ui/gfx/gpu_memory_buffer.h"
@@ skipping 105 matching lines @@
   gfx::BufferFormat GetFormat() const override { return format_; }
   void GetStride(int* stride) const override {
     int num_planes =
         static_cast<int>(gfx::NumberOfPlanesForBufferFormat(format_));
     for (int i = 0; i < num_planes; ++i)
       stride[i] =
           base::checked_cast<int>(StrideInBytes(size_.width(), format_, i));
   }
   gfx::GpuMemoryBufferId GetId() const override {
     NOTREACHED();
-    return 0;
+    return gfx::GpuMemoryBufferId(0);
   }
   gfx::GpuMemoryBufferHandle GetHandle() const override {
     gfx::GpuMemoryBufferHandle handle;
     handle.type = gfx::SHARED_MEMORY_BUFFER;
     handle.handle = shared_memory_->handle();
     return handle;
   }
   ClientBuffer AsClientBuffer() override {
     return reinterpret_cast<ClientBuffer>(this);
   }
@@ skipping 29 matching lines @@
     ClientBuffer buffer) {
   return reinterpret_cast<gfx::GpuMemoryBuffer*>(buffer);
 }
 
 void TestGpuMemoryBufferManager::SetDestructionSyncPoint(
     gfx::GpuMemoryBuffer* buffer,
     uint32 sync_point) {
 }
 
 }  // namespace cc