Tolerate GetRoot() returning null.

content/browser/accessibility/browser_accessibility_manager_android.cc

 // Copyright 2013 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/accessibility/browser_accessibility_manager_android.h"
 
 #include <cmath>
 
 #include "base/android/jni_android.h"
 #include "base/android/jni_string.h"
@@ skipping 174 matching lines @@
       }
       break;
     default:
       // There are some notifications that aren't meaningful on Android.
       // It's okay to skip them.
       break;
   }
 }
 
 jint BrowserAccessibilityManagerAndroid::GetRootId(JNIEnv* env, jobject obj) {
-  return static_cast<jint>(GetRoot()->GetId());
+  if (GetRoot())
+    return static_cast<jint>(GetRoot()->GetId());
+  else
+    return -1;
 }
 
 jboolean BrowserAccessibilityManagerAndroid::IsNodeValid(
     JNIEnv* env, jobject obj, jint id) {
   return GetFromID(id) != NULL;
 }
 
 void BrowserAccessibilityManagerAndroid::HitTest(
     JNIEnv* env, jobject obj, jint x, jint y) {
   if (delegate())
@@ skipping 571 matching lines @@
 BrowserAccessibilityManagerAndroid::UseRootScrollOffsetsWhenComputingBounds() {
   // The Java layer handles the root scroll offset.
   return false;
 }
 
 bool RegisterBrowserAccessibilityManager(JNIEnv* env) {
   return RegisterNativesImpl(env);
 }
 
 }  // namespace content