Support reading command line options for non-rooted devices for testing

This CL add a new flag "Enable command line on non-rooted devices" to
chrome://flags. If changed, it will set a flag in Chrome SharedPreferences.
And when CommandLineInitUtil starts, it checks whether an alternative
command line file could be used when:
1. The current build is "eng" or "userdebug" or
2. adb is enable and this is the debug app or
3. The flag is enable in SharedPreferences.

Bug: 784947
Change-Id: I0ee0d2eadbc8b2f1b49b5e5959f7e72f8feda80d
Reviewed-by: Yaron Friedman <>
Reviewed-by: Ted Choc <>
Reviewed-by: Luke Halliwell <>
Commit-Queue: Lei Tian <>
Cr-Commit-Position: refs/heads/master@{#539909}
11 files changed