Tablet WM : Swiping on system tray bubble.

ash/system/tray/system_tray_test_api.h

Index: ash/system/tray/system_tray_test_api.h
diff --git a/ash/system/tray/system_tray_test_api.h b/ash/system/tray/system_tray_test_api.h
index 4dfed95c520a2e496882e3adc6e1cb2a695f1d25..7bb3a78447e89249ac6328e0657f57f881e4d19d 100644
--- a/ash/system/tray/system_tray_test_api.h
+++ b/ash/system/tray/system_tray_test_api.h
@@ -28,6 +28,9 @@ class SystemTrayTestApi {
   }
   TraySystemInfo* tray_system_info() { return tray_->tray_system_info_; }
   TrayTiles* tray_tiles() { return tray_->tray_tiles_; }
+  void set_in_maximize_mode(bool in_maximize_mode) {
+    tray_->in_maximize_mode_ = in_maximize_mode;
+  }
 
  private:
   SystemTray* const tray_;