Fix shelf auto-hide calculation for app-list visibility.

ash/common/wm_shell.h

Index: ash/common/wm_shell.h
diff --git a/ash/common/wm_shell.h b/ash/common/wm_shell.h
index b7adf68b69edb12a1230eb3f5a131ec648ae1cdd..8dbedf31fa47dcd368c5655b1d53b922b0e40cb1 100644
--- a/ash/common/wm_shell.h
+++ b/ash/common/wm_shell.h
@@ -19,6 +19,7 @@
 #include "components/ui_devtools/devtools_server.h"
 #include "ui/base/ui_base_types.h"
 #include "ui/compositor/layer_type.h"
+#include "ui/display/types/display_constants.h"
 #include "ui/wm/public/window_types.h"
 
 namespace base {
@@ -275,10 +276,13 @@ class ASH_EXPORT WmShell {
 
   // Returns app list actual visibility. This might differ from
   // GetAppListTargetVisibility() when hiding animation is still in flight.
-  bool IsApplistVisible() const;
+  // Pass a valid display id to check target visibility for a specific display.

[James Cook, 2016/11/30 23:27:19]

If you don't pass a valid id what does it check? Just primary display or all
displays?

+  bool IsApplistVisible(int64_t display_id = display::kInvalidDisplayId) const;
 
   // Returns app list target visibility.
-  bool GetAppListTargetVisibility() const;
+  // Pass a valid display id to check visibility for a specific display.
+  bool GetAppListTargetVisibility(
+      int64_t display_id = display::kInvalidDisplayId) const;

[James Cook, 2016/11/30 23:27:19]

optional: I wonder if these methods would be clearer if they didn't use default
parameters, but had two explicit versions of each method. Then it would be
clearer that IsAppListVisible() means visible-anywhere and
IsAppListVisible(display_id) means just that display. The fact that you're using
kInvalidDisplayId to mean "any display" is kind of an implementation detail.

(And I see there are 55 callers of GetAppListTargetVisibility() so it's quite
reasonable not to change all the callers to pass an explicit display id.)

 
   // Returns true if a window is currently pinned.
   virtual bool IsPinned() = 0;