Consider TextInputController::inputMethodController() could be nullptr.

components/test_runner/text_input_controller.h

 // 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.
 
 #ifndef COMPONENTS_TEST_RUNNER_TEXT_INPUT_CONTROLLER_H_
 #define COMPONENTS_TEST_RUNNER_TEXT_INPUT_CONTROLLER_H_
 
 #include <string>
 #include <vector>
 
@@ skipping 29 matching lines @@
   void SetMarkedText(const std::string& text, int start, int length);
   bool HasMarkedText();
   std::vector<int> MarkedRange();
   std::vector<int> SelectedRange();
   std::vector<int> FirstRectForCharacterRange(unsigned location,
                                               unsigned length);
   void SetComposition(const std::string& text);
   void ForceTextInputStateUpdate();
 
   blink::WebView* view();
-  blink::WebInputMethodController* inputMethodController();
+  // Returns the WebInputMethodController corresponding to the focused frame
+  // accepting IME. Could return nullptr if no such frame exists.
+  blink::WebInputMethodController* GetInputMethodController();
 
   WebViewTestProxyBase* web_view_test_proxy_base_;
 
   base::WeakPtrFactory<TextInputController> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(TextInputController);
 };
 
 }  // namespace test_runner
 
 #endif  // COMPONENTS_TEST_RUNNER_TEXT_INPUT_CONTROLLER_H_