autotest: Collect log of chart process in camerabox chart fixture.

Redirect stdout/stderr of chart process to log file and collect the log
file in cleanup stage of camerabox test.

BUG=b:140256285
TEST=test_that <DUT>
cheets_CTS_P.9.0_r10.arm.CtsCameraTestCases.camerabox.front
--args="chart=<CHART>"

Change-Id: I0bd9d77632647ddeb33b91623df13d72d5b70bdd
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/autotest/+/2100700
Tested-by: Kuo Jen Wei <inker@chromium.org>
Reviewed-by: Rohit Makasana <rohitbm@chromium.org>
Commit-Queue: Kuo Jen Wei <inker@chromium.org>

server/cros/camerabox_utils.py

diff --git a/server/cros/camerabox_utils.py b/server/cros/camerabox_utils.py
index ff8a7e0..491c87e 100644
--- a/server/cros/camerabox_utils.py
+++ b/server/cros/camerabox_utils.py
@@ -16,31 +16,39 @@
 class ChartFixture:
     """Sets up chart tablet to display dummy scene image."""
     DISPLAY_SCRIPT = '/usr/local/autotest/bin/display_chart.py'
+    OUTPUT_LOG = '/tmp/chart_service.log'
 
     def __init__(self, chart_host, scene_uri):
         self.host = chart_host
         self.scene_uri = scene_uri
         self.display_pid = None
+        self.host.run(['rm', '-f', self.OUTPUT_LOG])
 
     def initialize(self):
         """Prepare scene file and display it on chart host."""
         logging.info('Prepare scene file')
-        chart_dir = self.host.get_tmp_dir()
+        tmpdir = self.host.get_tmp_dir()
         scene_path = os.path.join(
-                chart_dir, self.scene_uri[self.scene_uri.rfind('/') + 1:])
+                tmpdir, self.scene_uri[self.scene_uri.rfind('/') + 1:])
         self.host.run('wget', args=('-O', scene_path, self.scene_uri))
-        self.host.run('chmod', args=('-R', '755', chart_dir))
 
         logging.info('Display scene file')
         self.display_pid = self.host.run_background(
-                'python2 %s %s' % (self.DISPLAY_SCRIPT, scene_path))
+                'python2 {script} {scene} >{log} 2>&1'.format(
+                        script=self.DISPLAY_SCRIPT,
+                        scene=scene_path,
+                        log=self.OUTPUT_LOG))
         # TODO(inker): Suppose chart should be displayed very soon. Or require
         # of waiting until chart actually displayed.
 
     def cleanup(self):
         """Cleanup display script."""
         if self.display_pid is not None:
-            self.host.run('kill', args=('-2', str(self.display_pid)))
+            self.host.run(
+                    'kill',
+                    args=('-2', str(self.display_pid)),
+                    ignore_status=True)
+            self.host.get_file(self.OUTPUT_LOG, '.')
 
 
 def get_chart_address(host_address, args):