Make ThumbnailGenerator::AskForSnapshot support high DPI.

content/renderer/render_widget.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 "content/renderer/render_widget.h"
 
 #include "base/bind.h"
 #include "base/command_line.h"
 #include "base/debug/trace_event.h"
 #include "base/logging.h"
@@ skipping 1435 matching lines @@
     // given, to avoid leaking it.
     Send(new ViewHostMsg_PaintAtSize_ACK(routing_id_, tag, desired_size));
     return;
   }
 
   // Map the given DIB ID into this process, and unmap it at the end
   // of this function.
   scoped_ptr<TransportDIB> paint_at_size_buffer(
       TransportDIB::CreateWithHandle(dib_handle));
 
-  gfx::Size canvas_size = page_size;
-  float x_scale = static_cast<float>(desired_size.width()) /
+  gfx::Size page_size_in_pixel = page_size.Scale(device_scale_factor_);
+  gfx::Size desired_size_in_pixel = desired_size.Scale(device_scale_factor_);
+  gfx::Size canvas_size = page_size_in_pixel;
+  float x_scale = static_cast<float>(desired_size_in_pixel.width()) /
                   static_cast<float>(canvas_size.width());
-  float y_scale = static_cast<float>(desired_size.height()) /
+  float y_scale = static_cast<float>(desired_size_in_pixel.height()) /
                   static_cast<float>(canvas_size.height());
 
   gfx::Rect orig_bounds(canvas_size);
   canvas_size.set_width(static_cast<int>(canvas_size.width() * x_scale));
   canvas_size.set_height(static_cast<int>(canvas_size.height() * y_scale));
   gfx::Rect bounds(canvas_size);
 
   scoped_ptr<skia::PlatformCanvas> canvas(
       paint_at_size_buffer->GetPlatformCanvas(canvas_size.width(),
                                               canvas_size.height()));
@@ skipping 323 matching lines @@
   Send(new ViewHostMsg_BeginSmoothScroll(routing_id_, down, scroll_far));
 }
 
 bool RenderWidget::WillHandleMouseEvent(const WebKit::WebMouseEvent& event) {
   return false;
 }
 
 bool RenderWidget::WebWidgetHandlesCompositorScheduling() const {
   return false;
 }