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

ash/switchable_windows.cc

Index: ash/switchable_windows.cc
diff --git a/ash/switchable_windows.cc b/ash/switchable_windows.cc
index e735c32b3fac2b0179e2c83ca297115b934ffeb7..e7ecd7258d8a8c9ebdcaf59c03e6cd1633505ea9 100644
--- a/ash/switchable_windows.cc
+++ b/ash/switchable_windows.cc
@@ -13,6 +13,7 @@ const int kSwitchableWindowContainerIds[] = {
     kShellWindowId_DefaultContainer,
     kShellWindowId_AlwaysOnTopContainer,
     kShellWindowId_PanelContainer,
+    kShellWindowId_DockedContainer,

[flackr, 2015/04/07 15:08:38]

Lacking MRU information, I believe we arrange window selection order by the
order here. I'd expect docked windows to come before attached panels.

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

Thanks, done.

     kShellWindowId_AppListContainer};
 
 const size_t kSwitchableWindowContainerIdsLength =