Scale to DIPs in ppb_graphics2d_impl for proper invalidation

webkit/plugins/ppapi/ppb_graphics_2d_impl.h

Index: webkit/plugins/ppapi/ppb_graphics_2d_impl.h
diff --git a/webkit/plugins/ppapi/ppb_graphics_2d_impl.h b/webkit/plugins/ppapi/ppb_graphics_2d_impl.h
index cec39c61e5e24785525c456a9a8fe03adfd980d7..12a4c44d5bcecd571cd94b5e990524f1d6a9c43b 100644
--- a/webkit/plugins/ppapi/ppb_graphics_2d_impl.h
+++ b/webkit/plugins/ppapi/ppb_graphics_2d_impl.h
@@ -15,6 +15,7 @@
 #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;
@@ -75,6 +76,12 @@ class PPB_Graphics2D_Impl : public ::ppapi::Resource,
 
   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);