Refactor intra-strip panel drags by introducing PanelDragController.

chrome/browser/ui/panels/panel_browser_window_gtk.cc

Index: chrome/browser/ui/panels/panel_browser_window_gtk.cc
diff --git a/chrome/browser/ui/panels/panel_browser_window_gtk.cc b/chrome/browser/ui/panels/panel_browser_window_gtk.cc
index 34ca5430b4a4268dd2272b333a8684938ea9a9a7..a271a2b623d7e944083b53b94fd1fbb7d2cd0b44 100644
--- a/chrome/browser/ui/panels/panel_browser_window_gtk.cc
+++ b/chrome/browser/ui/panels/panel_browser_window_gtk.cc
@@ -470,7 +470,8 @@ void PanelBrowserWindowGtk::WillProcessEvent(GdkEvent* event) {
 
 void PanelBrowserWindowGtk::DidProcessEvent(GdkEvent* event) {
   DCHECK(last_mouse_down_);
-  if (event->type != GDK_MOTION_NOTIFY || !panel_->draggable())
+  if (event->type != GDK_MOTION_NOTIFY ||
+      !panel_->manager()->CanDrag(panel_.get()))
     return;
 
   gdouble new_x_double;
@@ -500,7 +501,7 @@ void PanelBrowserWindowGtk::DidProcessEvent(GdkEvent* event) {
   }
 
   if (drag_widget_) {
-    panel_->manager()->Drag(new_x - old_x);
+    panel_->manager()->Drag(new_x - old_x, new_y - old_y);
     gdk_event_free(last_mouse_down_);
     last_mouse_down_ = gdk_event_copy(event);
   }