firmware_ECKeyboard: Add delay for dev console.

Add a short delay after invoking the dev console to prevent characters
being dropped.  For some devices, the beginning characters appeared to
be missing/dropped.

BUG=chrome-os-partner:56274
BRANCH=None
TEST=Run firmware_ECKeyboard against chell 10 times and verify it passes
each time.

Change-Id: I199cea287fd9e9bb6080c66b87340484812b1ba8
Signed-off-by: Aseda Aboagye <aaboagye@google.com>
Reviewed-on: https://chromium-review.googlesource.com/413305
Commit-Ready: Nicolas Boichat <drinkcat@chromium.org>
Tested-by: Aseda Aboagye <aaboagye@chromium.org>
Reviewed-by: danny chan <dchan@chromium.org>
Reviewed-by: Wai-Hong Tam <waihong@google.com>
(cherry picked from commit 1a8c4704549ae17d752404c182efa4e6ce12aacd)
Reviewed-on: https://chromium-review.googlesource.com/469407
Reviewed-by: Aseda Aboagye <aaboagye@chromium.org>
Commit-Queue: Jongpil Jung <jongpil19.jung@samsung.corp-partner.google.com>
Tested-by: Jongpil Jung <jongpil19.jung@samsung.corp-partner.google.com>
diff --git a/server/site_tests/firmware_ECKeyboard/firmware_ECKeyboard.py b/server/site_tests/firmware_ECKeyboard/firmware_ECKeyboard.py
index 04327bb..6051f8f 100644
--- a/server/site_tests/firmware_ECKeyboard/firmware_ECKeyboard.py
+++ b/server/site_tests/firmware_ECKeyboard/firmware_ECKeyboard.py
@@ -18,6 +18,9 @@
     # Delay between commands
     CMD_DELAY = 1
 
+    # Delay to wait until developer console is open.
+    DEV_CONSOLE_DELAY = 2
+
     def initialize(self, host, cmdline_args):
         super(firmware_ECKeyboard, self).initialize(host, cmdline_args)
         # Only run in normal mode
@@ -31,7 +34,7 @@
         self.ec.key_up('<f2>')
         self.ec.key_up('<alt_l>')
         self.ec.key_up('<ctrl_l>')
-        time.sleep(self.CMD_DELAY)
+        time.sleep(self.DEV_CONSOLE_DELAY)
 
     def reboot_by_keyboard(self):
         """