Remove unused include in sequenced_worker_pool.h

cc/blimp/remote_compositor_bridge_client.h

 // Copyright 2016 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 CC_BLIMP_REMOTE_COMPOSITOR_BRIDGE_CLIENT_H_
 #define CC_BLIMP_REMOTE_COMPOSITOR_BRIDGE_CLIENT_H_
 
 #include <unordered_map>
 
 #include "base/macros.h"
 #include "cc/base/cc_export.h"
 
-namespace base {
-class SingleThreadTaskRunner;
-}  // namespace base
-
 namespace gfx {
 class ScrollOffset;
 }  // namespace gfx
 
 namespace cc {
 class CompositorProtoState;
 
 class CC_EXPORT RemoteCompositorBridgeClient {
  public:
   using ScrollOffsetMap = std::unordered_map<int, gfx::ScrollOffset>;
@@ skipping 11 matching lines @@
   // fail, for instance, if the layer present in the update was destroyed on the
   // engine.
   virtual bool ApplyScrollAndScaleUpdateFromClient(
       const ScrollOffsetMap& client_scroll_map,
       float client_page_scale) = 0;
 };
 
 }  // namespace cc
 
 #endif  // CC_BLIMP_REMOTE_COMPOSITOR_BRIDGE_CLIENT_H_