Add PanelBrowserTitlebarGtk for panels on GTK.

chrome/browser/ui/gtk/browser_titlebar.h

Index: chrome/browser/ui/gtk/browser_titlebar.h
diff --git a/chrome/browser/ui/gtk/browser_titlebar.h b/chrome/browser/ui/gtk/browser_titlebar.h
index cbdfe05c29eb42b2900b3e62742e159d7ecfd1c0..ff0fce24b1da5ddc3e0d7a33bda5571423338435 100644
--- a/chrome/browser/ui/gtk/browser_titlebar.h
+++ b/chrome/browser/ui/gtk/browser_titlebar.h
@@ -91,6 +91,14 @@ class BrowserTitlebar : public content::NotificationObserver,
 
   AvatarMenuButtonGtk* avatar_button() { return avatar_button_.get(); }
 
+ protected:
+  // Builds the button as denoted by |button_token|. Returns true if the button
+  // is created successfully.
+  virtual bool BuildButton(const std::string& button_token, bool left_side);
+
+  // Show the menu that the user gets from left-clicking the favicon.
+  virtual void ShowFaviconMenu(GdkEventButton* event);
+
  private:
   // A helper class to keep track of which frame of the throbber animation
   // we're showing.
@@ -131,9 +139,9 @@ class BrowserTitlebar : public content::NotificationObserver,
 
   // Constructs a CustomDraw button given 3 image ids (IDR_), the box to place
   // the button into, and a tooltip id (IDS_).
-  CustomDrawButton* BuildTitlebarButton(int image, int image_pressed,
-                                        int image_hot, GtkWidget* box,
-                                        bool start, int tooltip);
+  CustomDrawButton* CreateTitlebarButton(int image, int image_pressed,
+                                         int image_hot, GtkWidget* box,
+                                         int tooltip);
 
   // Update the titlebar spacing based on the custom frame and maximized state.
   void UpdateTitlebarAlignment();
@@ -146,9 +154,6 @@ class BrowserTitlebar : public content::NotificationObserver,
   // incognito spy guy.
   void UpdateAvatar();
 
-  // Show the menu that the user gets from left-clicking the favicon.
-  void ShowFaviconMenu(GdkEventButton* event);
-
   // The maximize button was clicked, take an action depending on which mouse
   // button the user pressed.
   void MaximizeButtonClicked();
@@ -191,8 +196,6 @@ class BrowserTitlebar : public content::NotificationObserver,
   // Overriden from ActiveWindowWatcherXObserver.
   virtual void ActiveWindowChanged(GdkWindow* active_window) OVERRIDE;
 
-  bool IsTypePanel();
-
   // Whether to display the avatar image.
   bool ShouldDisplayAvatar();