android: Fix ContentViewCore and RenderWidgetHostViewAndroid lifetime issue

content/browser/android/content_view_core_impl.cc

Index: content/browser/android/content_view_core_impl.cc
diff --git a/content/browser/android/content_view_core_impl.cc b/content/browser/android/content_view_core_impl.cc
index 4cb6da8994f4dd65a52654b0104c558c83adf513..72febdbf15a0e4f70b6ed46509783c646f31fb32 100644
--- a/content/browser/android/content_view_core_impl.cc
+++ b/content/browser/android/content_view_core_impl.cc
@@ -1679,6 +1679,13 @@ void ContentViewCoreImpl::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,