DialogSurfaceManager implementation.

content/public/android/java/src/org/chromium/content/app/ChildProcessServiceImpl.java

 // Copyright 2016 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.
 
 package org.chromium.content.app;
 
 import android.content.Context;
 import android.content.Intent;
 import android.graphics.SurfaceTexture;
 import android.os.Binder;
@@ skipping 379 matching lines @@
 
         try {
             SurfaceWrapper wrapper = mCallback.getViewSurface(surfaceId);
             return wrapper != null ? wrapper.getSurface() : null;
         } catch (RemoteException e) {
             Log.e(TAG, "Unable to call getViewSurface: %s", e);
             return null;
         }
     }
 
+    @SuppressWarnings("unused")
+    @CalledByNative
+    private IBinder getAndroidOverlayProvider() {
+        try {

[boliu, 2017/02/08 00:01:58]

all the other calls have a null check for mCallback

+            return mCallback.getAndroidOverlayProvider();
+        } catch (RemoteException e) {
+            Log.e(TAG, "Unable to call getAndroidOverlayProvider: %s", e);
+            return null;
+        }
+    }
+
     /**
      * Helper for registering FileDescriptorInfo objects with GlobalFileDescriptors.
      * This includes the IPC channel, the crash dump signals and resource related
      * files.
      */
     private static native void nativeRegisterGlobalFileDescriptor(
             int id, int fd, long offset, long size);
 
     /**
      * The main entry point for a child process. This should be called from a new thread since
      * it will not return until the child process exits. See child_process_service.{h,cc}
      *
      * @param serviceImpl The current ChildProcessServiceImpl object.
      * renderer.
      */
     private static native void nativeInitChildProcessImpl(
             ChildProcessServiceImpl serviceImpl, int cpuCount, long cpuFeatures);
 
     /**
      * Force the child process to exit.
      */
     private static native void nativeExitChildProcess();
 
     private native void nativeShutdownMainThread();
 }