Fix Mac window frame coordinate conversion on multiple monitor setups

chrome/browser/automation/automation_provider_mac.mm

Index: chrome/browser/automation/automation_provider_mac.mm
diff --git a/chrome/browser/automation/automation_provider_mac.mm b/chrome/browser/automation/automation_provider_mac.mm
index b475f4d4e02d536bcfc53be54c506cd1525235bc..e17d59c9b9b2c013d4483a963ab10cb3de9b4e54 100644
--- a/chrome/browser/automation/automation_provider_mac.mm
+++ b/chrome/browser/automation/automation_provider_mac.mm
@@ -22,10 +22,11 @@ void AutomationProvider::SetWindowBounds(int handle, const gfx::Rect& bounds,
   if (window) {
     NSRect new_bounds = NSRectFromCGRect(bounds.ToCGRect());
 
-    // This is likely incorrect for a multiple-monitor setup; OK because this
-    // is used only for testing purposes.
-    new_bounds.origin.y = [[window screen] frame].size.height -
-        new_bounds.origin.y - new_bounds.size.height;
+    if ([[NSScreen screens] count] > 0) {
+      new_bounds.origin.y =
+          [[[NSScreen screens] objectAtIndex:0] frame].size.height -
+          new_bounds.origin.y - new_bounds.size.height;
+    }
 
     [window setFrame:new_bounds display:NO];
     *success = true;