[Android] Fix ime NPE after RWH is destroyed

content/browser/renderer_host/ime_adapter_android.h

Index: content/browser/renderer_host/ime_adapter_android.h
diff --git a/content/browser/renderer_host/ime_adapter_android.h b/content/browser/renderer_host/ime_adapter_android.h
index b59576c0e365b7c2bc81d2ec907e0c4a87347d50..d55f0d532ac5885397baa01088812dc1b61d7b99 100644
--- a/content/browser/renderer_host/ime_adapter_android.h
+++ b/content/browser/renderer_host/ime_adapter_android.h
@@ -11,6 +11,7 @@
 
 namespace content {
 
+class RenderWidgetHostImpl;
 class RenderWidgetHostViewAndroid;
 struct NativeWebKeyboardEvent;
 
@@ -58,6 +59,8 @@ class ImeAdapterAndroid {
   void CancelComposition();
 
  private:
+  RenderWidgetHostImpl* GetRenderWidgetHostImpl();
+
   RenderWidgetHostViewAndroid* rwhva_;
   JavaObjectWeakGlobalRef java_ime_adapter_;
 };