Change panel drag related methods to use mouse location in screen coordinates.

chrome/browser/ui/panels/panel_drag_controller.h

Index: chrome/browser/ui/panels/panel_drag_controller.h
diff --git a/chrome/browser/ui/panels/panel_drag_controller.h b/chrome/browser/ui/panels/panel_drag_controller.h
index a58b7644077813d31c2cd5fda3a5ed3d4ede0079..df944a586e685d5958d7d40e9d3f160d675f9d53 100644
--- a/chrome/browser/ui/panels/panel_drag_controller.h
+++ b/chrome/browser/ui/panels/panel_drag_controller.h
@@ -19,8 +19,10 @@ class PanelDragController {
   PanelDragController();
   ~PanelDragController();
 
-  void StartDragging(Panel* panel);
-  void Drag(int delta_x, int delta_y);
+  // Drags the given panel.
+  // |mouse_location| is in screen coordinate system.
+  void StartDragging(Panel* panel, const gfx::Point& mouse_location);
+  void Drag(const gfx::Point& mouse_location);
   void EndDragging(bool cancelled);
 
   // Asynchronous confirmation of panel having been closed.
@@ -42,6 +44,10 @@ class PanelDragController {
   // dragging.
   gfx::Point dragging_panel_original_position_;
 
+  // The mouse location, in screen coordinates, when StartDragging or Drag was
+  // pveviously called.
+  gfx::Point last_mouse_location_;
+
   DISALLOW_COPY_AND_ASSIGN(PanelDragController);
 };