ui: Cleanup class/struct forward declarations

ui/compositor/test/in_process_context_factory.h

 // 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.
 
 #ifndef UI_COMPOSITOR_TEST_IN_PROCESS_CONTEXT_FACTORY_H_
 #define UI_COMPOSITOR_TEST_IN_PROCESS_CONTEXT_FACTORY_H_
 
 #include <stdint.h>
 #include <memory>
 
 #include "base/macros.h"
 #include "cc/surfaces/display.h"
 #include "cc/test/test_gpu_memory_buffer_manager.h"
 #include "cc/test/test_image_factory.h"
 #include "cc/test/test_shared_bitmap_manager.h"
 #include "cc/test/test_task_graph_runner.h"
 #include "ui/compositor/compositor.h"
 
-namespace base {
-class Thread;
-}
-
 namespace cc {
 class SurfaceManager;
 }
 
 namespace ui {
 class InProcessContextProvider;
 
 class InProcessContextFactory : public ContextFactory {
  public:
   // surface_manager is owned by the creator of this and must outlive the
@@ skipping 57 matching lines @@
 
   base::hash_map<Compositor*, std::unique_ptr<cc::Display>>
       per_compositor_data_;
 
   DISALLOW_COPY_AND_ASSIGN(InProcessContextFactory);
 };
 
 }  // namespace ui
 
 #endif  // UI_COMPOSITOR_TEST_IN_PROCESS_CONTEXT_FACTORY_H_