Combobox: Rename styles to STYLE_NORMAL and STYLE_ACTION and modify behaviors

ui/views/controls/combobox/combobox.h

Index: ui/views/controls/combobox/combobox.h
diff --git a/ui/views/controls/combobox/combobox.h b/ui/views/controls/combobox/combobox.h
index 20b65e0a4c06b9a9ca095aef60c123bfdd2acab2..6f2ab34928c204ba557745b8e070793e13d37e61 100644
--- a/ui/views/controls/combobox/combobox.h
+++ b/ui/views/controls/combobox/combobox.h
@@ -119,8 +119,16 @@ class VIEWS_EXPORT Combobox : public MenuDelegate,
   virtual void ButtonPressed(Button* sender, const ui::Event& event) OVERRIDE;
 
  private:
+  // The sources of the clicking event of the text button.
+  enum ClickEventSource {
+    CLICK_EVENT_SOURCE_MENU_ITEM,
+    CLICK_EVENT_SOURCE_MOUSE,
+    CLICK_EVENT_SOURCE_KEYBOARD,
+  };
+
   FRIEND_TEST_ALL_PREFIXES(ComboboxTest, Click);
   FRIEND_TEST_ALL_PREFIXES(ComboboxTest, NotifyOnClickWithMouse);
+  FRIEND_TEST_ALL_PREFIXES(ComboboxTest, ContentWidth);
 
   // Updates the combobox's content from its model.
   void UpdateFromModel();
@@ -150,7 +158,7 @@ class VIEWS_EXPORT Combobox : public MenuDelegate,
   int GetDisclosureArrowRightPadding() const;
 
   // Handles the clicking event.
-  void HandleClickEvent();
+  void HandleClickEvent(ClickEventSource source);
 
   // Our model. Not owned.
   ui::ComboboxModel* model_;