Add ability to have active window autohide shelf

ash/common/wm/window_state.h

Index: ash/common/wm/window_state.h
diff --git a/ash/common/wm/window_state.h b/ash/common/wm/window_state.h
index c7f2a1634ba1b03beb3b7725d053dac5e4387ef3..c120bbd1aee9d498c4612ac26be328d8d4a4a6cc 100644
--- a/ash/common/wm/window_state.h
+++ b/ash/common/wm/window_state.h
@@ -201,6 +201,15 @@ class ASH_EXPORT WindowState {
     hide_shelf_when_fullscreen_ = value;
   }
 
+  // Gets/sets whether the shelf should be hidden when this window is currently
+  // active. Note: if true, this will override the logic controlled by
+  // hide_shelf_when_fullscreen.

[oshima, 2017/03/30 14:01:27]

shelf control is effective only when it's active in general (same in
set_hide_shelf_when_fullscreen).

We probably should consolidate them into one method + enum, but we can do that
later when we need sticky support.

[yorkelee, 2017/03/30 19:34:12]

Renamed to autohide_shelf_when_fullscreen_or_maximized

+  bool hide_shelf_when_active() const { return hide_shelf_when_active_; }
+
+  void set_hide_shelf_when_active(bool value) {
+    hide_shelf_when_active_ = value;
+  }
+
   // If the minimum visibility is true, ash will try to keep a
   // minimum amount of the window is always visible on the work area
   // when shown.
@@ -369,6 +378,7 @@ class ASH_EXPORT WindowState {
   bool in_immersive_fullscreen_;
   bool ignore_keyboard_bounds_change_ = false;
   bool hide_shelf_when_fullscreen_;
+  bool hide_shelf_when_active_;
   bool minimum_visibility_;
   bool can_be_dragged_;
   bool cached_always_on_top_;