Implementation of device metrics emulation in render view.

content/renderer/render_widget.h

Index: content/renderer/render_widget.h
===================================================================
--- content/renderer/render_widget.h	(revision 221161)
+++ content/renderer/render_widget.h	(working copy)
@@ -65,6 +65,7 @@
 }
 
 namespace content {
+class ContextMenuParams;
 class PepperPluginInstanceImpl;
 class RenderWidgetCompositor;
 class RenderWidgetTest;
@@ -213,6 +214,21 @@
 
   bool is_swapped_out() { return is_swapped_out_; }
 
+  // DeviceEmulator class manages device 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 DeviceEmulator;
+
+  // Emulates device and widget metrics. Supplied values override everything
+  // coming from host.
+  void EmulateDevice(bool enabled,
+                     const gfx::Size& device_size,
+                     const gfx::Rect& widget_rect,
+                     float device_scale_factor,
+                     bool fit_to_view);
+  void set_popup_device_emulator(DeviceEmulator* emulator);
+
  protected:
   // Friend RefCounted so that the dtor can be non-public. Using this class
   // without ref-counting is an error.
@@ -281,6 +297,9 @@
               const gfx::Rect& resizer_rect,
               bool is_fullscreen,
               ResizeAck resize_ack);
+  virtual void SetDeviceEmulationParameters(bool enabled,
+      float device_scale_factor, float root_layer_scale);
+  virtual void OnShowHostContextMenu(ContextMenuParams* params);
 
   // RenderWidget IPC message handlers
   void OnHandleInputEvent(const WebKit::WebInputEvent* event,
@@ -738,6 +757,11 @@
   int outstanding_ime_acks_;
 #endif
 
+  scoped_ptr<DeviceEmulator> device_emulator_;
+
+  // Popup has a weak ptr to the device emulator of creator.
+  base::WeakPtr<DeviceEmulator> popup_device_emulator_;
+
   base::WeakPtrFactory<RenderWidget> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(RenderWidget);