Add VectorIconButton functionality to ImageButton.

ui/app_list/views/search_box_view.h

Index: ui/app_list/views/search_box_view.h
diff --git a/ui/app_list/views/search_box_view.h b/ui/app_list/views/search_box_view.h
index 3c37a29958952580236bf0718e769732d58aec1f..e0937c216cdeb25133f2cf2fb53a889fa0774edf 100644
--- a/ui/app_list/views/search_box_view.h
+++ b/ui/app_list/views/search_box_view.h
@@ -42,7 +42,7 @@ class SearchBoxImageButton;
 // contents and selection model of the Textfield.
 class APP_LIST_EXPORT SearchBoxView : public views::View,
                                       public views::TextfieldController,
-                                      public views::ButtonListener,
+                                      public views::ImageButtonDelegate,
                                       public SearchBoxModelObserver,
                                       public SpeechUIModelObserver {
  public:
@@ -78,7 +78,7 @@ class APP_LIST_EXPORT SearchBoxView : public views::View,
   // Sets voice label for Back button depending on whether a folder is open.
   void SetBackButtonLabel(bool folder);
 
-  // Overridden from views::View:
+  // views::View:
   gfx::Size GetPreferredSize() const override;
   bool OnMouseWheel(const ui::MouseWheelEvent& event) override;
   void OnEnabledChanged() override;
@@ -90,22 +90,22 @@ class APP_LIST_EXPORT SearchBoxView : public views::View,
   // Fires query change notification.
   void NotifyQueryChanged();
 
-  // Overridden from views::TextfieldController:
+  // views::TextfieldController:
   void ContentsChanged(views::Textfield* sender,
                        const base::string16& new_contents) override;
   bool HandleKeyEvent(views::Textfield* sender,
                       const ui::KeyEvent& key_event) override;
 
-  // Overridden from views::ButtonListener:
+  // views::ImageButtonDelegate:
   void ButtonPressed(views::Button* sender, const ui::Event& event) override;
 
-  // Overridden from SearchBoxModelObserver:
+  // SearchBoxModelObserver:
   void SpeechRecognitionButtonPropChanged() override;
   void HintTextChanged() override;
   void SelectionModelChanged() override;
   void TextChanged() override;
 
-  // Overridden from SpeechUIModelObserver:
+  // SpeechUIModelObserver:
   void OnSpeechRecognitionStateChanged(
       SpeechRecognitionState new_state) override;