We have a problem in the process on destroying WebContentsImpl because

content/browser/android/web_contents_observer_android.cc

 // 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.
 
 #include "content/browser/android/web_contents_observer_android.h"
 
 #include <string>
 
 #include <jni.h>
 
@@ skipping 30 matching lines @@
       reinterpret_cast<ContentViewCore*>(native_content_view_core);
   WebContentsObserverAndroid* native_observer = new WebContentsObserverAndroid(
       env, obj, content_view_core->GetWebContents());
   return reinterpret_cast<intptr_t>(native_observer);
 }
 
 void WebContentsObserverAndroid::Destroy(JNIEnv* env, jobject obj) {
   delete this;
 }
 
-void WebContentsObserverAndroid::WebContentsDestroyed(
-    WebContents* web_contents) {
+void WebContentsObserverAndroid::WebContentsDestroyed() {
   JNIEnv* env = AttachCurrentThread();
   ScopedJavaLocalRef<jobject> obj(weak_java_observer_.get(env));
   if (obj.is_null()) {
     delete this;
   } else {
     // The java side will destroy |this|
     Java_WebContentsObserverAndroid_detachFromWebContents(env, obj.obj());
   }
 }
 
@@ skipping 216 matching lines @@
   if (obj.is_null())
     return;
   Java_WebContentsObserverAndroid_didFirstVisuallyNonEmptyPaint(
       env, obj.obj());
 }
 
 bool RegisterWebContentsObserverAndroid(JNIEnv* env) {
   return RegisterNativesImpl(env);
 }
 }  // namespace content