Call TSF's SetFocus iff the current focused document manager is expected ones

ui/base/win/tsf_bridge.cc

 // Copyright (c) 2012 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 <msctf.h>
 #include "base/logging.h"
 #include "base/memory/ref_counted.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/memory/singleton.h"
 #include "base/message_loop.h"
@@ skipping 86 matching lines @@
 
     DCHECK(text_store_.get());
     text_store_.reset();
     client_id_ = TF_CLIENTID_NULL;
   }
 
   // TsfBridge override.
   virtual bool EnableIME() OVERRIDE {
     DCHECK_EQ(MessageLoop::TYPE_UI, MessageLoop::current()->type());
     DCHECK(IsInitialized());
-    if (SUCCEEDED(thread_manager_->SetFocus(document_manager_))) {
-      return true;
-    }
-    return false;
+
+    // Since EnableIME and DisableIME are designed to be a swap operation of
+    // |document_manager_| and |disabled_document_manager_|, do nothing unless
+    // the current focused document manager is |disabled_document_manager_|.
+    // In other words, ITfThreadMgr::SetFocus should be called if and only if
+    // TsfBridge actually has TSF input focus. Otherwise, TSF input focus will
+    // be inconsistent with Win32 input focus.
+    if (!IsFocused(disabled_document_manager_))
+      return false;
+
+    return SUCCEEDED(thread_manager_->SetFocus(document_manager_));
   }
 
   // TsfBridge override.
   virtual bool DisableIME() OVERRIDE {
     DCHECK_EQ(MessageLoop::TYPE_UI, MessageLoop::current()->type());
     DCHECK(IsInitialized());
-    if (SUCCEEDED(thread_manager_->SetFocus(disabled_document_manager_))) {
-      return true;
-    }
-    return false;
+
+    // Do nothing unless the current focused document manager is
+    // |document_manager_|. See the comment in EnableIME.
+    if (!IsFocused(document_manager_))
+      return false;
+
+    return SUCCEEDED(thread_manager_->SetFocus(disabled_document_manager_));
   }
 
   // TsfBridge override.
   virtual bool CancelComposition() OVERRIDE {
     DCHECK_EQ(MessageLoop::TYPE_UI, MessageLoop::current()->type());
     DCHECK(IsInitialized());
-    // If current focused document manager is not |document_manager_|, do
+    // If the current focused document manager is not |document_manager_|, do
     // nothing here.
-    base::win::ScopedComPtr<ITfDocumentMgr> focused_document_mangaer;
-    if (FAILED(thread_manager_->GetFocus(focused_document_mangaer.Receive())))
-      return false;
-    if (!focused_document_mangaer.IsSameObject(document_manager_))
+    if (!IsFocused(document_manager_))
       return false;
 
     base::win::ScopedComPtr<ITfContext> context;
     if (FAILED(document_manager_->GetTop(context.Receive()))) {
       VLOG(1) << "Failed to get top context.";
       return false;
     }
 
     base::win::ScopedComPtr<ITfContextOwnerCompositionServices> owner;
     if (FAILED(owner.QueryFrom(context))) {
@@ skipping 143 matching lines @@
     }
 
     if (FAILED(disabled_document_manager_->Push(disabled_context))) {
       VLOG(1) << "Failed to push disabled context.";
       return false;
     }
 
     return true;
   }
 
+  // Returns true if |document_manager| is the focused document manager.
+  bool IsFocused(base::win::ScopedComPtr<ITfDocumentMgr> document_manager) {
+    base::win::ScopedComPtr<ITfDocumentMgr> focused_document_mangaer;
+    if (FAILED(thread_manager_->GetFocus(focused_document_mangaer.Receive())))
+      return false;
+    return focused_document_mangaer.IsSameObject(document_manager);
+  }
+
   // Returns true if already initialized.
   bool IsInitialized() {
     return client_id_ != TF_CLIENTID_NULL;
   }
 
   // An ITfContext object to be used in normal text field.
   base::win::ScopedComPtr<ITfDocumentMgr> document_manager_;
 
   // Altough TSF support IME enable/disable switching without context changing,
   // some IMEs don't change their state. So we should switch a focus to a
@@ skipping 51 matching lines @@
     VLOG(1) << "Do not use TsfBridge without UI thread.";
     return NULL;
   }
   TsfBridgeDelegate* delegate =
       static_cast<TsfBridgeDelegate*>(tls_tsf_bridge.Get());
   DCHECK(delegate) << "Do no call GetInstance before TsfBridge::Initialize.";
   return delegate;
 }
 
 }  // namespace ui