Cleanup: Remove unneeded forward declarations in ppapi.

ppapi/tests/test_graphics_2d.h

 // 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.
 
-#ifndef PAPPI_TESTS_TEST_GRAPHICS_2D_H_
-#define PAPPI_TESTS_TEST_GRAPHICS_2D_H_
+#ifndef PPAPI_TESTS_TEST_GRAPHICS_2D_H_
+#define PPAPI_TESTS_TEST_GRAPHICS_2D_H_
+
+#include <string>
 
 #include "ppapi/c/pp_stdint.h"
 #include "ppapi/tests/test_case.h"
 
 struct PPB_Graphics2D;
 struct PPB_ImageData;
-struct PPB_Testing_Dev;
 
 namespace pp {
 class Graphics2D;
 class ImageData;
 class Point;
 class Rect;
 }
 
 class TestGraphics2D : public TestCase {
  public:
-  TestGraphics2D(TestingInstance* instance) : TestCase(instance) {}
+  explicit TestGraphics2D(TestingInstance* instance) : TestCase(instance) {}
 
   // TestCase implementation.
   virtual bool Init();
   virtual void RunTest();
 
   void QuitMessageLoop();
 
  private:
   bool ReadImageData(const pp::Graphics2D& dc,
                      pp::ImageData* image,
@@ skipping 42 matching lines @@
   std::string TestPaint();
   std::string TestScroll();
   std::string TestReplace();
   std::string TestFlush();
 
   // Used by the tests that access the C API directly.
   const PPB_Graphics2D* graphics_2d_interface_;
   const PPB_ImageData* image_data_interface_;
 };
 
-#endif  // PAPPI_TESTS_TEST_GRAPHICS_2D_H_
+#endif  // PPAPI_TESTS_TEST_GRAPHICS_2D_H_