Enables storing shelf's auto_hide_behavior and alignment per display.

chrome/common/pref_names.cc

Index: chrome/common/pref_names.cc
diff --git a/chrome/common/pref_names.cc b/chrome/common/pref_names.cc
index b7945dbf854803dce7bd88d43e78365214d71436..13388f7aa638b6c300033394ef66e95cbd002e25 100644
--- a/chrome/common/pref_names.cc
+++ b/chrome/common/pref_names.cc
@@ -2091,6 +2091,8 @@ const char kMediaGalleriesRememberedGalleries[] =
 // set its value is set from the synced value (once prefs have been
 // synced). This gives a per-machine setting that is initialized from the last
 // set value.
+// These values are default on the machine but can be overridden by per-display
+// values in kShelfPreferences.

[bartfab (slow), 2012/12/14 21:34:02]

... unless overridden by managed policy, in which case these values take
precedence again :). I think that should be noted here.

Sorry for being so nit-picky but the behavior is non-obvious and it is very
useful to document it properly.

[Jun Mukai, 2012/12/14 22:44:56]

Done.

 // String value corresponding to ash::Shell::ShelfAlignment.
 const char kShelfAlignment[] = "shelf_alignment";
 const char kShelfAlignmentLocal[] = "shelf_alignment_local";
@@ -2100,6 +2102,11 @@ const char kShelfAutoHideBehaviorLocal[] = "auto_hide_behavior_local";
 const char kPinnedLauncherApps[] = "pinned_launcher_apps";
 // Boolean value indicating whether to show a logout button in the ash tray.
 const char kShowLogoutButtonInTray[] = "show_logout_button_in_tray";
+// Dictionary value that holds per-display preference of shelf alignment and
+// auto-hide behavior. Key of the dictionary is the id of the display, and
+// its value is a dictionary whose keys are kShelfAlignment and
+// kShelfAutoHideBehavior.
+const char kShelfPreferences[] = "shelf_preferences";
 
 const char kFlingVelocityCap[] = "gesture.fling_velocity_cap";
 const char kLongPressTimeInSeconds[] =