CCA: Add the missing chdir() in cca.py

It's wrongly removed when addressing comment in
https://crrev.com/c/1892972/15/chrome/browser/resources/chromeos/camera/utils/cca.py#243

Bug: 1019581
Test: Run cca.py outside of the CCA directory.
Change-Id: I2d190385e35d6ac35831db1c4a75f2ca66f4b05e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1921605
Commit-Queue: Shik Chen <shik@chromium.org>
Commit-Queue: Wei Lee <wtlee@chromium.org>
Auto-Submit: Shik Chen <shik@chromium.org>
Reviewed-by: Wei Lee <wtlee@chromium.org>
Cr-Commit-Position: refs/heads/master@{#716105}

chrome/browser/resources/chromeos/camera/utils/cca.py

@@ -263,6 +263,7 @@ def ParseArgs(args):
 def Main(args):
   cca_root = os.path.dirname(os.path.dirname(os.path.realpath(__file__)))
   assert os.path.basename(cca_root) == 'camera'
+  os.chdir(cca_root)
 
   args = ParseArgs(args)