Adds the speech recognition button to the app-list searchbox.

ui/app_list/search_box_model_observer.h

Index: ui/app_list/search_box_model_observer.h
diff --git a/ui/app_list/search_box_model_observer.h b/ui/app_list/search_box_model_observer.h
index b4cc40c2d9a3f1dde7b9c716c9665d2baf4148eb..97b9849ca148a6c9f1b6a7bc9282135f01038e11 100644
--- a/ui/app_list/search_box_model_observer.h
+++ b/ui/app_list/search_box_model_observer.h
@@ -14,6 +14,13 @@ class APP_LIST_EXPORT SearchBoxModelObserver {
   // Invoked when icon is changed.
   virtual void IconChanged() = 0;
 
+  // Invoked when the some properties of the right button (icon image or
+  // tooltip) is changed.
+  virtual void RightButtonPropChanged() = 0;
+
+  // Invoked when the right button state is changed.
+  virtual void RightButtonStateChanged(bool toggled) = 0;
+
   // Invoked when hint text is changed.
   virtual void HintTextChanged() = 0;