Enable chrome.automation.getDesktop on all aura platforms.

chrome/browser/ui/ash/accessibility/ax_root_obj_wrapper.cc

Index: chrome/browser/ui/ash/accessibility/ax_root_obj_wrapper.cc
diff --git a/chrome/browser/ui/ash/accessibility/ax_root_obj_wrapper.cc b/chrome/browser/ui/ash/accessibility/ax_root_obj_wrapper.cc
index 366955d1a355431b1b4b6938a22822c83f22369b..df98f32da1538725bd0118acc3425312688d9fd6 100644
--- a/chrome/browser/ui/ash/accessibility/ax_root_obj_wrapper.cc
+++ b/chrome/browser/ui/ash/accessibility/ax_root_obj_wrapper.cc
@@ -4,14 +4,18 @@
 
 #include "chrome/browser/ui/ash/accessibility/ax_root_obj_wrapper.h"
 
-#include "ash/shell.h"
 #include "base/strings/utf_string_conversions.h"
 #include "ui/accessibility/ax_node_data.h"
 #include "ui/accessibility/ax_view_state.h"
 #include "ui/aura/window.h"
+#include "ui/aura/window_tree_host.h"
 #include "ui/views/accessibility/ax_aura_obj_cache.h"
 #include "ui/views/accessibility/ax_window_obj_wrapper.h"
 
+#if defined(OS_CHROMEOS)
+#include "ash/shell.h"
+#endif
+
 AXRootObjWrapper::AXRootObjWrapper(int32 id)
     : id_(id), alert_window_(new aura::Window(NULL)) {
 }
@@ -45,10 +49,7 @@ views::AXAuraObjWrapper* AXRootObjWrapper::GetParent() {
 
 void AXRootObjWrapper::GetChildren(
     std::vector<views::AXAuraObjWrapper*>* out_children) {
-  if (!ash::Shell::HasInstance())
-    return;
-
-  // Only on ash is there a notion of a root with children.
+#if defined(OS_CHROMEOS)

[oshima, 2015/03/20 22:31:42]

I still don't quite understand why you need this.

When/how you're getting null shell? Do you have the stack trace?

The only way you can get null shell is when you run Windows in desktop mode
only. (no WinAsh) but If you're not on ash, this method shouldn't be called?

   aura::Window::Windows children =
       ash::Shell::GetInstance()->GetAllRootWindows();
   for (size_t i = 0; i < children.size(); ++i) {
@@ -58,6 +59,9 @@ void AXRootObjWrapper::GetChildren(
 
   out_children->push_back(
       views::AXAuraObjCache::GetInstance()->GetOrCreate(alert_window_));
+#else
+  views::AXAuraObjCache::GetInstance()->GetTopLevelWindows(out_children);
+#endif
 }
 
 void AXRootObjWrapper::Serialize(ui::AXNodeData* out_node_data) {