remove unnecessary bitmapdevice references

TBR=

Author: reed@google.com

Review URL: https://codereview.chromium.org/354143004
diff --git a/bench/DisplacementBench.cpp b/bench/DisplacementBench.cpp
index 881ba33..2a0f7c0 100644
--- a/bench/DisplacementBench.cpp
+++ b/bench/DisplacementBench.cpp
@@ -4,8 +4,8 @@
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
+
 #include "Benchmark.h"
-#include "SkBitmapDevice.h"
 #include "SkBitmapSource.h"
 #include "SkCanvas.h"
 #include "SkDisplacementMapEffect.h"