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)
@@ -22,6 +22,7 @@
 #include "content/renderer/paint_aggregator.h"
 #include "ipc/ipc_listener.h"
 #include "ipc/ipc_sender.h"
+#include "skia/ext/platform_canvas.h"
 #include "third_party/WebKit/public/platform/WebRect.h"
 #include "third_party/WebKit/public/web/WebCompositionUnderline.h"
 #include "third_party/WebKit/public/web/WebPopupType.h"
@@ -54,6 +55,7 @@
 class WebKeyboardEvent;
 class WebMouseEvent;
 class WebTouchEvent;
+class WebTouchPoint;
 struct WebPoint;
 struct WebRenderingStatsImpl;
 }
@@ -65,9 +67,11 @@
 }
 
 namespace content {
+class DeviceEmulationEventRewriter;
 class PepperPluginInstanceImpl;
 class RenderWidgetCompositor;
 class RenderWidgetTest;
+struct ContextMenuParams;
 struct GpuRenderingStats;
 struct WebPluginGeometry;
 
@@ -282,6 +286,16 @@
               bool is_fullscreen,
               ResizeAck resize_ack);
 
+  // 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);
+  // This sets a tranformation on root compositor layer.
+  virtual void SetDeviceEmulationScale(float scale);
+
   // RenderWidget IPC message handlers
   void OnHandleInputEvent(const WebKit::WebInputEvent* event,
                           const ui::LatencyInfo& latency_info,
@@ -296,6 +310,7 @@
   virtual void OnWasHidden();
   virtual void OnWasShown(bool needs_repainting);
   virtual void OnWasSwappedOut();
+  void OnEmulateDeviceAck(bool enabled);
   void OnUpdateRectAck();
   void OnCreateVideoAck(int32 video_id);
   void OnUpdateVideoAck(int32 video_id);
@@ -738,6 +753,77 @@
   int outstanding_ime_acks_;
 #endif
 
+  // Helper class which is managing device emulation. 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 DeviceEmulationHelper {
+   public:
+    DeviceEmulationHelper(const gfx::Size& device_size,
+                          const gfx::Rect& widget_rect,
+                          float device_scale_factor,
+                          bool fit_to_view);
+    virtual ~DeviceEmulationHelper();
+
+    void BeginEmulation(RenderWidget* widget);
+    void ChangeEmulationParams(RenderWidget* widget,
+                               DeviceEmulationHelper* params);
+    void EndEmulation(RenderWidget* widget);
+
+    // The following methods alter handlers' behavior for messages related to
+    // widget size and position.
+    void OnResizeMessage(RenderWidget* widget,
+                         const ViewMsg_Resize_Params& params);
+    void OnUpdateScreenRectsMessage(RenderWidget* widget,
+                                    const gfx::Rect view_screen_rect,
+                                    const gfx::Rect window_screen_rect);
+    void OnShowContextMenu(RenderWidget* widget, ContextMenuParams* params);
+
+    WebKit::WebInputEvent* ConvertInputEventToEmulated(
+        RenderWidget* widget, const WebKit::WebInputEvent* event);
+
+    // Created popups need to be repositioned.
+    void PopupCreated(RenderWidget* widget, RenderWidget* popup);
+    WebKit::WebRect ConvertPopupScreenRectFromEmulated(
+        RenderWidget* popup, const WebKit::WebRect& rect);
+
+   private:
+    void Apply(RenderWidget* widget, float overdraw_bottom_height,
+        gfx::Rect resizer_rect, bool is_fullscreen);
+
+    // Parameters as passed by WebViewClient::EmulateDevice.
+    gfx::Size device_size_;
+    gfx::Rect widget_rect_;
+    float device_scale_factor_;
+    bool fit_to_view_;
+
+    // The computed scaled used to fit widget into browser window.
+    float scale_;
+
+    // Original values to restore back after emulation ends.
+    gfx::Size original_size_;
+    gfx::Size original_physical_backing_size_;
+    WebKit::WebScreenInfo original_screen_info_;
+    gfx::Rect original_view_screen_rect_;
+    gfx::Rect original_window_screen_rect_;
+
+    // This handles the rewriting of input events incoming to the widget and
+    // the compositor.
+    scoped_ptr<DeviceEmulationEventRewriter> input_event_rewriter_;
+
+    base::WeakPtrFactory<DeviceEmulationHelper> weak_ptr_factory_;
+  };
+
+  scoped_ptr<DeviceEmulationHelper> device_emulation_helper_;
+
+  // Popup has a weak ptr to the device emulation helper of creator.
+  base::WeakPtr<DeviceEmulationHelper> popup_device_emulation_helper_;
+
+  // While we send ViewMsg_EmulateDevice to the host, these store the requested
+  // emulation parameters.
+  scoped_ptr<DeviceEmulationHelper> pending_device_emulation_helper_;
+  bool pending_device_emulation_enabled_;
+
   base::WeakPtrFactory<RenderWidget> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(RenderWidget);