(Chrome OS) Notify when the candidate window is opened/closed.

chrome/browser/chromeos/input_method/candidate_window.h

Index: chrome/browser/chromeos/input_method/candidate_window.h
diff --git a/chrome/browser/chromeos/input_method/candidate_window.h b/chrome/browser/chromeos/input_method/candidate_window.h
index 062db49ebf66081d7b108594446954c8879fabad..c6f87d25904ee66d6d886a5d07888879fe9f32a6 100644
--- a/chrome/browser/chromeos/input_method/candidate_window.h
+++ b/chrome/browser/chromeos/input_method/candidate_window.h
@@ -21,12 +21,23 @@ namespace input_method {
 // rendering the candidate view is deleted.
 class CandidateWindowController {
  public:
+  class Observer {
+   public:
+    virtual ~Observer() {}
+
+    virtual void CandidateWindowOpened() = 0;
+    virtual void CandidateWindowClosed() = 0;
+  };
+
   CandidateWindowController();
   virtual ~CandidateWindowController();
 
   // Initializes the candidate window. Returns true on success.
   bool Init();
 
+  void AddObserver(Observer* observer);
+  void RemoveObserver(Observer* observer);
+
  private:
   class Impl;
   Impl* impl_;