ChromeOS: implement per-user time zone preferences.

Historically ChromeOS had only one global time zone preference. But now time
settings become complicate and we need to support per-user time zone
preferences.

[email protected]

BUG=622555,699472
CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.linux:closure_compilation

Review-Url: https://codereview.chromium.org/2849823003
Cr-Commit-Position: refs/heads/master@{#493673}
diff --git a/chrome/browser/about_flags.cc b/chrome/browser/about_flags.cc
index 5d33e79..0429a755 100644
--- a/chrome/browser/about_flags.cc
+++ b/chrome/browser/about_flags.cc
@@ -3204,7 +3204,10 @@
      flag_descriptions::kDisableNewVirtualKeyboardBehaviorName,
      flag_descriptions::kDisableNewVirtualKeyboardBehaviorDescription, kOsCrOS,
      SINGLE_DISABLE_VALUE_TYPE(switches::kDisableNewVirtualKeyboardBehavior)},
-#endif  // defined(OS_CHROMEOS)
+    {"enable-per-user-timezone", flag_descriptions::kEnablePerUserTimezoneName,
+     flag_descriptions::kEnablePerUserTimezoneDescription, kOsCrOS,
+     SINGLE_DISABLE_VALUE_TYPE(chromeos::switches::kDisablePerUserTimezone)},
+#endif  // OS_CHROMEOS
 
 #if !defined(OS_ANDROID)
     {"enable-picture-in-picture",