Support detaching/attaching panels via inter-strip drags.

chrome/browser/ui/panels/native_panel.h

Index: chrome/browser/ui/panels/native_panel.h
diff --git a/chrome/browser/ui/panels/native_panel.h b/chrome/browser/ui/panels/native_panel.h
index 2298b77119fdc5a4f98b94457b8a048e177c4855..87ee8fe05528a294397cb285ef4af4df4f293a6e 100644
--- a/chrome/browser/ui/panels/native_panel.h
+++ b/chrome/browser/ui/panels/native_panel.h
@@ -87,6 +87,9 @@ class NativePanel {
   // Sets whether the panel app icon is visible (usually refers to the app icons
   // in the desktop bar).
   virtual void SetPanelAppIconVisibility(bool visible) = 0;
+
+  // Sets whether the panel window is always on top.
+  virtual void SetPanelAlwaysOnTop(bool on_top) = 0;
 };
 
 // A NativePanel utility interface used for accessing elements of the
@@ -96,9 +99,11 @@ class NativePanelTesting {
   static NativePanelTesting* Create(NativePanel* native_panel);
   virtual ~NativePanelTesting() {}
 
-  virtual void PressLeftMouseButtonTitlebar(const gfx::Point& point) = 0;
+  // |mouse_location| is in screen coordinates.
+  virtual void PressLeftMouseButtonTitlebar(
+      const gfx::Point& mouse_location) = 0;
   virtual void ReleaseMouseButtonTitlebar() = 0;
-  virtual void DragTitlebar(int delta_x, int delta_y) = 0;
+  virtual void DragTitlebar(const gfx::Point& mouse_location) = 0;
   virtual void CancelDragTitlebar() = 0;
   virtual void FinishDragTitlebar() = 0;