[Android] Handle a null java side of CVC in context menu

chrome/browser/ui/android/context_menu_helper.cc

Index: chrome/browser/ui/android/context_menu_helper.cc
diff --git a/chrome/browser/ui/android/context_menu_helper.cc b/chrome/browser/ui/android/context_menu_helper.cc
index a5db63633d49deb7dfd8f23fb3b30e031a4fab93..a941dd533bc073ab4bc5bd82b4d8befa2333018b 100644
--- a/chrome/browser/ui/android/context_menu_helper.cc
+++ b/chrome/browser/ui/android/context_menu_helper.cc
@@ -41,12 +41,18 @@ void ContextMenuHelper::ShowContextMenu(
   if (!content_view_core)
     return;
 
+  base::android::ScopedJavaLocalRef<jobject> jcontent_view_core(
+      content_view_core->GetJavaObject());
+
+  if (jcontent_view_core.is_null())
+    return;
+
   JNIEnv* env = base::android::AttachCurrentThread();
   context_menu_params_ = params;
   Java_ContextMenuHelper_showContextMenu(
       env,
       java_obj_.obj(),
-      content_view_core->GetJavaObject().obj(),
+      jcontent_view_core.obj(),
       ContextMenuHelper::CreateJavaContextMenuParams(params).obj());
 }