Move the 'Exit session' button to the most left side in the system tray.

ash/common/system/chromeos/palette/palette_tray.cc

Index: ash/common/system/chromeos/palette/palette_tray.cc
diff --git a/ash/common/system/chromeos/palette/palette_tray.cc b/ash/common/system/chromeos/palette/palette_tray.cc
index 29129125e32c3f8cb3cc35ff621958a39d79211e..8bbe5899b125a328d0ce434c2e075291b437afae 100644
--- a/ash/common/system/chromeos/palette/palette_tray.cc
+++ b/ash/common/system/chromeos/palette/palette_tray.cc
@@ -327,7 +327,7 @@ gfx::Rect PaletteTray::GetAnchorRect(
     if (tray_container()->border())
       icon_size -= tray_container()->border()->GetInsets().width();
 
-    r.Offset(-r.width() + icon_size, 0);
+    r.Offset(-r.width() + icon_size + x(), 0);
   } else {
     // Vertical layout doesn't need the border adjustment that horizontal needs.
     r.Offset(0, -r.height() + tray_container()->height());