[Android] Fix ime NPE after RWH is destroyed

content/browser/renderer_host/ime_adapter_android.h

 // 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.
 
 #ifndef CONTENT_BROWSER_RENDERER_HOST_IME_ADAPTER_ANDROID_H_
 #define CONTENT_BROWSER_RENDERER_HOST_IME_ADAPTER_ANDROID_H_
 
 #include <jni.h>
 
 #include "base/android/jni_helper.h"
 
 namespace content {
 
+class RenderWidgetHostImpl;
 class RenderWidgetHostViewAndroid;
 struct NativeWebKeyboardEvent;
 
 // This class is in charge of dispatching key events from the java side
 // and forward to renderer along with input method results via
 // corresponding host view.
 // Ownership of these objects remains on the native side (see
 // RenderWidgetHostViewAndroid).
 class ImeAdapterAndroid {
  public:
@@ skipping 27 matching lines @@
   void SelectAll(JNIEnv*, jobject);
   void Cut(JNIEnv*, jobject);
   void Copy(JNIEnv*, jobject);
   void Paste(JNIEnv*, jobject);
   void ResetImeAdapter(JNIEnv*, jobject);
 
   // Called from native -> java
   void CancelComposition();
 
  private:
+  RenderWidgetHostImpl* GetRenderWidgetHostImpl();
+
   RenderWidgetHostViewAndroid* rwhva_;
   JavaObjectWeakGlobalRef java_ime_adapter_;
 };
 
 bool RegisterImeAdapter(JNIEnv* env);
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_RENDERER_HOST_IME_ADAPTER_ANDROID_H_