Add SetScale to PPB_WidgetDev, use scale for painting

webkit/plugins/ppapi/ppb_scrollbar_impl.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 "webkit/plugins/ppapi/ppb_scrollbar_impl.h"
 
 #include "base/bind.h"
 #include "base/logging.h"
 #include "base/message_loop.h"
 #include "ppapi/c/dev/ppp_scrollbar_dev.h"
@@ skipping 120 matching lines @@
   }
   scrollbar_->scroll(direction, granularity, fmultiplier);
 }
 
 PP_Bool PPB_Scrollbar_Impl::PaintInternal(const gfx::Rect& rect,
                                           PPB_ImageData_Impl* image) {
   ImageDataAutoMapper mapper(image);
   skia::PlatformCanvas* canvas = image->GetPlatformCanvas();
   if (!canvas || !scrollbar_.get())
     return PP_FALSE;
+  canvas->save();
+  canvas->scale(scale(), scale());
   scrollbar_->paint(webkit_glue::ToWebCanvas(canvas), rect);
+  canvas->restore();
 
 #if defined(OS_WIN)
   if (base::win::GetVersion() == base::win::VERSION_XP)
     skia::MakeOpaque(canvas, rect.x(), rect.y(), rect.width(), rect.height());
 #endif
 
   return PP_TRUE;
 }
 
 PP_Bool PPB_Scrollbar_Impl::HandleEventInternal(
@@ skipping 87 matching lines @@
   pp_rect.point.x = dirty_.x();
   pp_rect.point.y = dirty_.y();
   pp_rect.size.width = dirty_.width();
   pp_rect.size.height = dirty_.height();
   dirty_ = gfx::Rect();
   Invalidate(&pp_rect);
 }
 
 }  // namespace ppapi
 }  // namespace webkit