[FYI] All-in-one OnCandidateWindow{Show,Update,Hide}

ui/base/ime/input_method_imm32.cc

 // Copyright (c) 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "ui/base/ime/input_method_imm32.h"
 
 #include "base/basictypes.h"
 #include "ui/base/ime/composition_text.h"
 #include "ui/base/ime/text_input_client.h"
 #include "ui/base/ime/win/tsf_input_scope.h"
@@ skipping 217 matching lines @@
   imm32_manager_.DestroyImeWindow(window_handle);
   return 0;
 }
 
 LRESULT InputMethodIMM32::OnImeNotify(UINT message,
                                       WPARAM wparam,
                                       LPARAM lparam,
                                       BOOL* handled) {
   *handled = FALSE;
 
+  bool previous_state = is_candidate_popup_open_;
+
   // Update |is_candidate_popup_open_|, whether a candidate window is open.
   switch (wparam) {
   case IMN_OPENCANDIDATE:
     is_candidate_popup_open_ = true;
+    if (!previous_state)
+      OnCandidateWindowShown();
     break;
   case IMN_CLOSECANDIDATE:
     is_candidate_popup_open_ = false;
+    if (previous_state)
+      OnCandidateWindowHidden();
+    break;
+  case IMN_CHANGECANDIDATE:
+    // TODO(kochi): The IME API expects this event to notify window size change,
+    // while this may fire more often without window resize. There is no generic
+    // way to get bounds of candidate window.
+    OnCandidateWindowUpdated();
     break;
   }
 
   return 0;
 }
 
 void InputMethodIMM32::ConfirmCompositionText() {
   if (composing_window_handle_)
     imm32_manager_.CleanupComposition(composing_window_handle_);
 
@@ skipping 23 matching lines @@
       enabled_ = true;
       break;
   }
 
   imm32_manager_.SetTextInputMode(window_handle, text_input_mode);
   tsf_inputscope::SetInputScopeForTsfUnawareWindow(
       window_handle, text_input_type, text_input_mode);
 }
 
 }  // namespace ui