android: Fix ContentViewCore and RenderWidgetHostViewAndroid lifetime issue

content/browser/android/content_view_core_impl.cc

 // Copyright 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 "content/browser/android/content_view_core_impl.h"
 
 #include "base/android/jni_android.h"
 #include "base/android/jni_array.h"
 #include "base/android/jni_string.h"
 #include "base/android/scoped_java_ref.h"
@@ skipping 1661 matching lines @@
     const base::string16& result) {
   JNIEnv* env = AttachCurrentThread();
   ScopedJavaLocalRef<jobject> obj = java_ref_.get(env);
   if (obj.is_null())
     return;
   ScopedJavaLocalRef<jstring> jresult = ConvertUTF16ToJavaString(env, result);
   Java_ContentViewCore_onSmartClipDataExtracted(
       env, obj.obj(), jresult.obj());
 }
 
+void ContentViewCoreImpl::WebContentsDestroyed(WebContents* web_contents) {
+  WebContentsViewAndroid* wcva =
+      static_cast<WebContentsViewAndroid*>(web_contents->GetView());
+  DCHECK(wcva);
+  wcva->SetContentViewCore(NULL);
+}
+
 // This is called for each ContentView.
 jlong Init(JNIEnv* env, jobject obj,
            jboolean hardware_accelerated,
            jlong native_web_contents,
            jlong view_android,
            jlong window_android) {
   ContentViewCoreImpl* view = new ContentViewCoreImpl(
       env, obj, hardware_accelerated,
       reinterpret_cast<WebContents*>(native_web_contents),
       reinterpret_cast<ui::ViewAndroid*>(view_android),
       reinterpret_cast<ui::WindowAndroid*>(window_android));
   return reinterpret_cast<intptr_t>(view);
 }
 
 bool RegisterContentViewCore(JNIEnv* env) {
   return RegisterNativesImpl(env);
 }
 
 }  // namespace content