faft: Speed up the waiting time for dev screen and sync

Waiting for a dev screen and pressing Ctrl-D is a recurrent action.
Booting to a dev screen is a bit faster than other firmware screens,
like recovery insert screen. We can make the dev screen a separated
case from other firmware screens for speed-up. It can save 3 seconds
each time.

Also the sync delay can be faster, from 5 seconds to 2 seconds.

BUG=chromium-os:34392
TEST=run FAFT suite on Link and the dev screen timing is correct.

Change-Id: I377494cc44b4bb9ca3e2d2addee3cb34a2d511d0
Reviewed-on: https://gerrit.chromium.org/gerrit/38630
Reviewed-by: Vic Yang <victoryang@chromium.org>
Commit-Ready: Tom Wai-Hong Tam <waihong@chromium.org>
Tested-by: Tom Wai-Hong Tam <waihong@chromium.org>
diff --git a/server/cros/faftsequence.py b/server/cros/faftsequence.py
index 6121e9e..0c781ed 100644
--- a/server/cros/faftsequence.py
+++ b/server/cros/faftsequence.py
@@ -589,7 +589,7 @@
             # If changing FORCE_DEV_SWITCH_ON flag, reboot to get a clear state
             if ((gbb_flags ^ new_flags) & vboot.GBB_FLAG_FORCE_DEV_SWITCH_ON):
                 self.run_faft_step({
-                    'firmware_action': self.wait_fw_screen_and_ctrl_d,
+                    'firmware_action': self.wait_dev_screen_and_ctrl_d,
                 })
 
 
@@ -828,6 +828,12 @@
             self.servo.enter_key()
 
 
+    def wait_dev_screen_and_ctrl_d(self):
+        """Wait for firmware warning screen and press Ctrl-D."""
+        time.sleep(self.delay.dev_screen)
+        self.press_ctrl_d()
+
+
     def wait_fw_screen_and_ctrl_d(self):
         """Wait for firmware warning screen and press Ctrl-D."""
         time.sleep(self.delay.firmware_screen)
@@ -1032,7 +1038,7 @@
         """
         # Change the default firmware_action for dev mode passing the fw screen.
         self.register_faft_template({
-            'firmware_action': (self.wait_fw_screen_and_ctrl_d if dev_mode
+            'firmware_action': (self.wait_dev_screen_and_ctrl_d if dev_mode
                                 else None),
         })
         if dev_mode: