Allow Alt-Tab to move the focus to docked windows.

ash/wm/overview/window_selector.cc

Index: ash/wm/overview/window_selector.cc
diff --git a/ash/wm/overview/window_selector.cc b/ash/wm/overview/window_selector.cc
index 6230b9b7c50331bd1f818be81e233deedbbd7c59..25277c936bccd65556ec629aaaf5719d947fa92a 100644
--- a/ash/wm/overview/window_selector.cc
+++ b/ash/wm/overview/window_selector.cc
@@ -218,6 +218,16 @@ views::Widget* CreateTextFilter(views::TextfieldController* controller,
 const int WindowSelector::kTextFilterBottomEdge =
     kTextFilterDistanceFromTop + kTextFilterHeight;
 
+// static
+bool WindowSelector::IsSelectable(aura::Window* window) {
+  wm::WindowState* state = wm::GetWindowState(window);
+  if (state->GetStateType() == wm::WINDOW_STATE_TYPE_DOCKED ||
+      state->GetStateType() == wm::WINDOW_STATE_TYPE_DOCKED_MINIMIZED)
+    return false;
+  return window->type() == ui::wm::WINDOW_TYPE_NORMAL ||
+         window->type() == ui::wm::WINDOW_TYPE_PANEL;
+}
+
 WindowSelector::WindowSelector(WindowSelectorDelegate* delegate)
     : delegate_(delegate),
       restore_focus_window_(aura::client::GetFocusClient(
@@ -456,10 +466,8 @@ void WindowSelector::OnDisplayMetricsChanged(const gfx::Display& display,
 }
 
 void WindowSelector::OnWindowAdded(aura::Window* new_window) {
-  if (new_window->type() != ui::wm::WINDOW_TYPE_NORMAL &&
-      new_window->type() != ui::wm::WINDOW_TYPE_PANEL) {
+  if (!IsSelectable(new_window))
     return;
-  }
 
   for (size_t i = 0; i < kSwitchableWindowContainerIdsLength; ++i) {
     if (new_window->parent()->id() == kSwitchableWindowContainerIds[i] &&
@@ -568,8 +576,10 @@ void WindowSelector::HideAndTrackNonOverviewWindows() {
       for (aura::Window::Windows::const_iterator iter =
            container->children().begin(); iter != container->children().end();
            ++iter) {
-        if (!(*iter)->IsVisible() || (*grid_iter)->Contains(*iter))
+        if (!(*iter)->IsVisible() || (*grid_iter)->Contains(*iter) ||
+            !IsSelectable(*iter)) {

[flackr, 2015/04/07 15:08:39]

It's confusing that IsSelectable is not a subset of the windows in the mru
window list (i.e. mru window list checks ash::wm::CanActivateWindow). If it was,
we could remove HideAndTrackNonOverviewWindows as we would skip every remaining
window with this IsSelectable test.

It's probably too much for this CL, but we should check if
HideAndTrackNonOverviewWindows is necessary anymore (http://crbug.com/295862)
since with transient windows included in selection (http://crbug.com/304289) I
think it may no longer be needed.

[oshima, 2015/04/07 18:00:32]

My understanding is that WindowSelector accepts window list in Init, which
implies that it's independent of MRU list, at least conceptually (otherwise,
Init should be able to just use MRU window list inside).

If we can remove this, that'd be better. let me look into it.

[flackr, 2015/04/07 18:10:33]

This is historical from when we engaged overview automatically after a short
pause while alt tabbing. It is only ever initialized with the mru window list:
https://code.google.com/p/chromium/codesearch#chromium/src/ash/wm/overview/wi...
That'd be great.

[oshima, 2015/04/07 18:20:47]

WindowSelectorTest.NonActivatableWindowsHiddens fails without this code. I
assume we can remove this because there is no other non activatable windows to
hide?

[flackr, 2015/04/07 18:26:22]

I believe so. I can't think of any non activatable normal windows which are not
transient parents or children of an activatable window.

[oshima, 2015/04/07 20:35:29]

Done.

           continue;
+        }
         hidden_windows_.Add(*iter);
       }
     }