Move bit_cast from base/macros.h to its own header

ppapi/shared_impl/ppb_view_shared.cc

 // Copyright (c) 2012 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 "ppapi/shared_impl/ppb_view_shared.h"
 
+#include <string.h>
+
 namespace {
 
 bool IsRectNonempty(const PP_Rect& rect) {
   return rect.size.width > 0 && rect.size.height > 0;
 }
 
 }  // namespace
 
 namespace ppapi {
 
@@ skipping 65 matching lines @@
 float PPB_View_Shared::GetCSSScale() const { return data_.css_scale; }
 
 PP_Bool PPB_View_Shared::GetScrollOffset(PP_Point* scroll_offset) const {
   if (!scroll_offset)
     return PP_FALSE;
   *scroll_offset = data_.scroll_offset;
   return PP_TRUE;
 }
 
 }  // namespace ppapi