Add test cases for panel overflow handling.

chrome/browser/ui/panels/panel_manager.h

Index: chrome/browser/ui/panels/panel_manager.h
diff --git a/chrome/browser/ui/panels/panel_manager.h b/chrome/browser/ui/panels/panel_manager.h
index f14af903659c211a5ed4440dff13c71e65ea123a..a3e42056aa38a24dd3dd63afc01e1b8dc2a52eef 100644
--- a/chrome/browser/ui/panels/panel_manager.h
+++ b/chrome/browser/ui/panels/panel_manager.h
@@ -23,8 +23,6 @@ class PanelStrip;
 // This class manages a set of panels.
 class PanelManager : public AutoHidingDesktopBar::Observer {
  public:
-  typedef std::vector<Panel*> Panels;
-
   // Returns a single instance.
   static PanelManager* GetInstance();
 
@@ -72,7 +70,7 @@ class PanelManager : public AutoHidingDesktopBar::Observer {
 
   int num_panels() const;
   int StartingRightPosition() const;
-  const Panels& panels() const;
+  std::vector<Panel*> panels() const;
 
   AutoHidingDesktopBar* auto_hiding_desktop_bar() const {
     return auto_hiding_desktop_bar_;