Hook up Chrome's wallpaper picker for mash.

chrome/browser/chromeos/extensions/wallpaper_private_api.cc

Index: chrome/browser/chromeos/extensions/wallpaper_private_api.cc
diff --git a/chrome/browser/chromeos/extensions/wallpaper_private_api.cc b/chrome/browser/chromeos/extensions/wallpaper_private_api.cc
index 6e0f19be7c2df1bdf532af893a5833ba4d750da5..407ac9f430eaab8f3e5edf34e986c40d7008eb96 100644
--- a/chrome/browser/chromeos/extensions/wallpaper_private_api.cc
+++ b/chrome/browser/chromeos/extensions/wallpaper_private_api.cc
@@ -169,6 +169,11 @@ WindowStateManager* g_window_state_manager = NULL;
 // static
 void WindowStateManager::MinimizeInactiveWindows(
     const std::string& user_id_hash) {
+  if (!ash::Shell::HasInstance() || ash::Shell::GetInstance()->in_mus()) {

[sadrul, 2016/05/19 19:45:22]

If there's a Shell instance, it should never have in_mus() set here. i.e. the
in_mus() check shouldn't be needed.

You could also check chrome::IsRunningInMash() instead.

[msw, 2016/05/19 20:22:17]

Done.

+    NOTIMPLEMENTED();
+    return;
+  }
+
   if (!g_window_state_manager)
     g_window_state_manager = new WindowStateManager();
   g_window_state_manager->BuildWindowListAndMinimizeInactiveForUser(
@@ -177,6 +182,11 @@ void WindowStateManager::MinimizeInactiveWindows(
 
 // static
 void WindowStateManager::RestoreWindows(const std::string& user_id_hash) {
+  if (!ash::Shell::HasInstance() || ash::Shell::GetInstance()->in_mus()) {
+    NOTIMPLEMENTED();
+    return;
+  }
+
   if (!g_window_state_manager) {
     DCHECK(false) << "This should only be called after calling "
                   << "MinimizeInactiveWindows.";