DCHECK that jstring to C++ string conversions don't pass in null.

chrome/browser/android/tab_android.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 "chrome/browser/android/tab_android.h"
 
 #include <stddef.h>
 
 #include "base/android/jni_android.h"
 #include "base/android/jni_array.h"
@@ skipping 511 matching lines @@
     jint page_transition,
     const JavaParamRef<jstring>& j_referrer_url,
     jint referrer_policy,
     jboolean is_renderer_initiated,
     jboolean should_replace_current_entry,
     jlong intent_received_timestamp,
     jboolean has_user_gesture) {
   if (!web_contents())
     return PAGE_LOAD_FAILED;
 
+  if (url.is_null())
+    return PAGE_LOAD_FAILED;
+
   GURL gurl(base::android::ConvertJavaStringToUTF8(env, url));
   if (gurl.is_empty())
     return PAGE_LOAD_FAILED;
 
   // If the page was prerendered, use it.
   // Note in incognito mode, we don't have a PrerenderManager.
 
   prerender::PrerenderManager* prerender_manager =
       prerender::PrerenderManagerFactory::GetForProfile(GetProfile());
   if (prerender_manager) {
@@ skipping 374 matching lines @@
 static void Init(JNIEnv* env, const JavaParamRef<jobject>& obj) {
   TRACE_EVENT0("native", "TabAndroid::Init");
   // This will automatically bind to the Java object and pass ownership there.
   new TabAndroid(env, obj);
 }
 
 // static
 bool TabAndroid::RegisterTabAndroid(JNIEnv* env) {
   return RegisterNativesImpl(env);
 }