Scale to DIPs in ppb_graphics2d_impl for proper invalidation

webkit/plugins/ppapi/ppb_graphics_2d_impl.h

 // 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.
 
 #ifndef WEBKIT_PLUGINS_PPAPI_PPB_GRAPHICS_2D_IMPL_H_
 #define WEBKIT_PLUGINS_PPAPI_PPB_GRAPHICS_2D_IMPL_H_
 
 #include <vector>
 
 #include "base/basictypes.h"
 #include "base/memory/weak_ptr.h"
 #include "ppapi/c/pp_completion_callback.h"
 #include "ppapi/c/ppb_graphics_2d.h"
 #include "ppapi/shared_impl/resource.h"
 #include "ppapi/shared_impl/tracked_callback.h"
 #include "ppapi/thunk/ppb_graphics_2d_api.h"
 #include "third_party/WebKit/Source/WebKit/chromium/public/platform/WebCanvas.h"
+#include "webkit/plugins/webkit_plugins_export.h"
 
 namespace gfx {
 class Rect;
 }
 
 namespace webkit {
 namespace ppapi {
 
 class PPB_ImageData_Impl;
 class PluginInstance;
@@ skipping 40 matching lines @@
              const gfx::Rect& paint_rect);
 
   // Notifications about the view's progress painting.  See PluginInstance.
   // These messages are used to send Flush callbacks to the plugin.
   void ViewWillInitiatePaint();
   void ViewInitiatedPaint();
   void ViewFlushedPaint();
 
   PPB_ImageData_Impl* image_data() { return image_data_.get(); }
 
+  // Scale the rectangle, taking care to round coordinates outward so a
+  // rectangle scaled down then scaled back up by the inverse scale would
+  // fully contain the entire area affected by the original rectangle.
+  WEBKIT_PLUGINS_EXPORT static gfx::Rect ScaleRectBounds(const gfx::Rect& rect,
+                                                         float scale);
+
  private:
   explicit PPB_Graphics2D_Impl(PP_Instance instance);
 
   bool Init(int width, int height, bool is_always_opaque);
 
   // Tracks a call to flush that requires a callback.
   class FlushCallbackData {
    public:
     FlushCallbackData() {
       Clear();
@@ skipping 105 matching lines @@
 
   base::WeakPtrFactory<PPB_Graphics2D_Impl> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(PPB_Graphics2D_Impl);
 };
 
 }  // namespace ppapi
 }  // namespace webkit
 
 #endif  // WEBKIT_PLUGINS_PPAPI_PPB_GRAPHICS_2D_IMPL_H_