Disable incognito if parental controls are enabled on android.

Provides a hook to the Android application to specify whether parental
controls are enabled and incognito should be disabled.

TEST=build/android/test_runner.py gtest -s unit_tests
BUG=329276

Review URL: https://codereview.chromium.org/136693011

git-svn-id: http://src.chromium.org/chrome/trunk/src/testing@245390 4ff67af0-8c30-449e-8e8b-ad334ec8d88c