[IME] Removes the duplicated IMEs in chrome://settings/languages, and support async component IMEs …

ui/base/ime/chromeos/ime_bridge.cc

 // Copyright 2014 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/chromeos/ime_bridge.h"
 
 #include <map>
 #include "base/logging.h"
 #include "base/memory/singleton.h"
 
@@ skipping 48 matching lines @@
   virtual void SetCurrentEngineHandler(
       IMEEngineHandlerInterface* handler) OVERRIDE {
     engine_handler_ = handler;
   }
 
   // IMEBridge override.
   virtual IMEEngineHandlerInterface* SetCurrentEngineHandlerById(
       const std::string& engine_id) OVERRIDE {
     std::map<std::string, IMEEngineHandlerInterface*>::const_iterator itor =
         engine_handler_map_.find(engine_id);
-    // |engine_id| must be found unless it's empty, but if it's not found, fall
-    // back to NULL when non-debug build.
-    DCHECK(itor != engine_handler_map_.end() || engine_id.empty());
+    // It is normal in that the engine is not found, because sometimes the
+    // extension based xkb id may be provided but the xkb component extension
+    // is not installed, for example, in browser_tests.
     if (itor == engine_handler_map_.end()) {
       engine_handler_ = NULL;
       return NULL;
     }
 
     engine_handler_ = engine_handler_map_[engine_id];
     return engine_handler_;
   }
 
   // IMEBridge override.
@@ skipping 41 matching lines @@
   delete g_ime_bridge;
   g_ime_bridge = NULL;
 }
 
 // static.
 IMEBridge* IMEBridge::Get() {
   return g_ime_bridge;
 }
 
 }  // namespace chromeos