Implementation of device metrics emulation in render view.

content/renderer/render_widget.h

Index: content/renderer/render_widget.h
diff --git a/content/renderer/render_widget.h b/content/renderer/render_widget.h
index 0d606f88fde96790f280ed1cbbbc05939000aa3f..dbab73390d98d517094033597afdd32f6702d50c 100644
--- a/content/renderer/render_widget.h
+++ b/content/renderer/render_widget.h
@@ -65,9 +65,11 @@ class Range;
 }
 
 namespace content {
+class ExternalPopupMenu;
 class PepperPluginInstanceImpl;
 class RenderWidgetCompositor;
 class RenderWidgetTest;
+struct ContextMenuParams;
 struct GpuRenderingStats;
 struct WebPluginGeometry;
 
@@ -223,6 +225,22 @@ class CONTENT_EXPORT RenderWidget
 
   bool is_swapped_out() { return is_swapped_out_; }
 
+  // ScreenMetricsEmulator class manages screen emulation inside a render
+  // widget. This includes resizing, placing view on the screen at desired
+  // position, changing device scale factor, and scaling down the whole
+  // widget if required to fit into the browser window.
+  class ScreenMetricsEmulator;
+
+  // Emulates screen and widget metrics. Supplied values override everything
+  // coming from host.
+  void EnableScreenMetricsEmulation(
+      const gfx::Size& device_size,
+      const gfx::Rect& widget_rect,
+      float device_scale_factor,
+      bool fit_to_view);
+  void DisableScreenMetricsEmulation();
+  void SetPopupOriginAdjustmentsForEmulation(ScreenMetricsEmulator* emulator);
+
  protected:
   // Friend RefCounted so that the dtor can be non-public. Using this class
   // without ref-counting is an error.
@@ -291,6 +309,11 @@ class CONTENT_EXPORT RenderWidget
               const gfx::Rect& resizer_rect,
               bool is_fullscreen,
               ResizeAck resize_ack);
+  virtual void SetScreenMetricsEmulationParameters(
+      float device_scale_factor, float root_layer_scale);
+  void SetExternalPopupOriginAdjustmentsForEmulation(
+      ExternalPopupMenu* popup, ScreenMetricsEmulator* emulator);
+  virtual void OnShowHostContextMenu(ContextMenuParams* params);
 
   // RenderWidget IPC message handlers
   void OnHandleInputEvent(const WebKit::WebInputEvent* event,
@@ -752,6 +775,14 @@ class CONTENT_EXPORT RenderWidget
   int outstanding_ime_acks_;
 #endif
 
+  scoped_ptr<ScreenMetricsEmulator> screen_metrics_emulator_;
+
+  // Popups may be displaced when screen metrics emulation is enabled.
+  // These values are used to properly adjust popup position.
+  gfx::Point popup_view_origin_for_emulation_;
+  gfx::Point popup_screen_origin_for_emulation_;
+  float popup_origin_scale_for_emulation_;
+
   base::WeakPtrFactory<RenderWidget> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(RenderWidget);