Fix browser.memory_stats has no GPU and Renderer info on CrOS

BUG=284219
TEST=run related code on daisy
NOTRY=true

Review URL: https://chromiumcodereview.appspot.com/23745007

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@221637 0039d316-1c4b-4281-b951-d872f2087c98

tools/telemetry/telemetry/core/platform/cros_platform_backend.py

@@ -56,14 +56,13 @@ class CrosPlatformBackend(platform_backend.PlatformBackend):
   def GetChildPids(self, pid):
     """Returns a list of child pids of |pid|."""
     all_process_info = self._cri.ListProcesses()
-    processes = []
-    for pid, _, ppid, state in all_process_info:
-      processes.append((pid, ppid, state))
+    processes = [(curr_pid, curr_ppid, curr_state)
+                 for curr_pid, _, curr_ppid, curr_state in all_process_info]
     return proc_util.GetChildPids(processes, pid)
 
   def GetCommandLine(self, pid):
-    command = self._GetPsOutput(['command'], pid)
-    return command[0] if command else None
+    command = self._GetFileContents('/proc/%s/cmdline' % pid)
+    return command if command else None
 
   def CanFlushIndividualFilesFromSystemCache(self):
     return True