Refactor intra-strip panel drags by introducing PanelDragController.

chrome/browser/ui/panels/panel.cc

Index: chrome/browser/ui/panels/panel.cc
diff --git a/chrome/browser/ui/panels/panel.cc b/chrome/browser/ui/panels/panel.cc
index 6be51041e3c5363060c133ee003e2b2641c14221..6f041e233215e824d1efd393efe724940d2338d6 100644
--- a/chrome/browser/ui/panels/panel.cc
+++ b/chrome/browser/ui/panels/panel.cc
@@ -49,7 +49,6 @@ Panel::Panel(Browser* browser, const gfx::Size& requested_size)
       has_temporary_layout_(false),
       restored_size_(requested_size),
       auto_resizable_(false),
-      draggable_(true),
       expansion_state_(EXPANDED),
       old_expansion_state_(EXPANDED),
       app_icon_visible_(true) {
@@ -76,6 +75,10 @@ PanelManager* Panel::manager() const {
   return PanelManager::GetInstance();
 }
 
+bool Panel::draggable() const {
+  return panel_strip()->CanDragPanel(this);
+}
+
 const Extension* Panel::GetExtension() const {
   return GetExtensionFromBrowser(browser());
 }