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

ui/base/ime/input_method_tsf.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_tsf.h"
 
 #include "ui/base/ime/text_input_client.h"
 #include "ui/base/ime/win/tsf_bridge.h"
 #include "ui/base/ime/win/tsf_event_router.h"
 
 namespace ui {
 
 class InputMethodTSF::TSFEventObserver : public TSFEventRouterObserver {
  public:
-  TSFEventObserver() : is_candidate_popup_open_(false) {}
+  TSFEventObserver() : is_candidate_popup_open_(false), window_count_(0) {}
 
   // Returns true if we know for sure that a candidate window (or IME suggest,
   // etc.) is open.
   bool IsCandidatePopupOpen() const { return is_candidate_popup_open_; }
 
   // Overridden from TSFEventRouterObserver:
   virtual void OnCandidateWindowCountChanged(size_t window_count) OVERRIDE {
     is_candidate_popup_open_ = (window_count != 0);
+    if (window_count_ == 0 && window_count) {
+      ui::TSFBridge::GetInstance()->OnCandidateWindowShow();

[yukawa, 2013/11/25 05:07:42]

I'm not sure if we can safely call back external code from here.  Using PostTask
to avoid nested message handler might be safer.  Please note that objects that
implement TextInputClient can do anything (e.g., calling
InputMehotd::CancelComposition) at this line.

+    } else if (window_count_ && window_count) {
+      ui::TSFBridge::GetInstance()->OnCandidateWindowUpdate();
+    } else if (window_count_ && window_count == 0) {
+      ui::TSFBridge::GetInstance()->OnCandidateWindowHide();
+    }
+    window_count_ = window_count;
   }
 
  private:
   // True if we know for sure that a candidate window is open.
   bool is_candidate_popup_open_;
+  int window_count_;
 
   DISALLOW_COPY_AND_ASSIGN(TSFEventObserver);
 };
 
 InputMethodTSF::InputMethodTSF(internal::InputMethodDelegate* delegate,
                                HWND toplevel_window_handle)
     : InputMethodWin(delegate, toplevel_window_handle),
       tsf_event_observer_(new TSFEventObserver()),
       tsf_event_router_(new TSFEventRouter(tsf_event_observer_.get())) {
   // In non-Aura environment, appropriate callbacks to OnFocus() and OnBlur()
@@ skipping 111 matching lines @@
   }
   InputMethodWin::OnDidChangeFocusedClient(focused_before, focused);
 }
 
 void InputMethodTSF::ConfirmCompositionText() {
   if (!IsTextInputTypeNone())
     ui::TSFBridge::GetInstance()->ConfirmComposition();
 }
 
 }  // namespace ui