Fix pid calculation for browser on cros.

The correct browser process is the direct child of the session_manager.

BUG=241749
TEST=manual
NOTRY=True

Review URL: https://chromiumcodereview.appspot.com/16626005

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@204980 0039d316-1c4b-4281-b951-d872f2087c98

2 files changed, 40 insertions, 11 deletions

diff --git a/tools/telemetry/telemetry/core/chrome/cros_browser_backend.py b/tools/telemetry/telemetry/core/chrome/cros_browser_backend.py
index 70400e7..8650f52 100644
--- a/tools/telemetry/telemetry/core/chrome/cros_browser_backend.py
+++ b/tools/telemetry/telemetry/core/chrome/cros_browser_backend.py
@@ -146,12 +146,40 @@ class CrOSBrowserBackend(browser_backend.BrowserBackend):
 
     return args
 
+
+  def _GetSessionManagerPid(self, procs):
+    """Returns the pid of the session_manager process, given the list of
+    processes."""
+    for pid, process, _ in procs:
+      if process.startswith('/sbin/session_manager '):
+        return pid
+    return None
+
   @property
   def pid(self):
-    for pid, process in self._cri.ListProcesses():
+    """Locates the pid of the main chrome browser process.
+
+    Chrome on cros is usually in /opt/google/chrome, but could be in
+    /usr/local/ for developer workflows - debug chrome is too large to fit on
+    rootfs.
+
+    Chrome spawns multiple processes for renderers. pids wrap around after they
+    are exhausted so looking for the smallest pid is not always correct. We
+    locate the session_manager's pid, and look for the chrome process that's an
+    immediate child. This is the main browser process.
+    """
+    procs = self._cri.ListProcesses()
+    session_manager_pid = self._GetSessionManagerPid(procs)
+    if not session_manager_pid:
+      return None
+
+    # Find the chrome process that is the child of the session_manager.
+    for pid, process, ppid in procs:
+      if ppid != session_manager_pid:
+        continue
       for path in self.CHROME_PATHS:
         if process.startswith(path):
-          return int(pid)
+          return pid
     return None
 
   @property
diff --git a/tools/telemetry/telemetry/core/chrome/cros_interface.py b/tools/telemetry/telemetry/core/chrome/cros_interface.py
index 3207f5c..243dfca 100644
--- a/tools/telemetry/telemetry/core/chrome/cros_interface.py
+++ b/tools/telemetry/telemetry/core/chrome/cros_interface.py
@@ -236,18 +236,19 @@ class CrOSInterface(object):
         return res
 
   def ListProcesses(self):
+    """Returns a tuple (pid, cmd, ppid) of all processes on the device."""
     stdout, stderr = self.RunCmdOnDevice([
         '/bin/ps', '--no-headers',
         '-A',
-        '-o', 'pid,args'], quiet=True)
-    assert stderr == ''
+        '-o', 'pid,ppid,args'], quiet=True)
+    assert stderr == '', stderr
     procs = []
     for l in stdout.split('\n'): # pylint: disable=E1103
       if l == '':
         continue
-      m = re.match('^\s*(\d+)\s+(.+)', l, re.DOTALL)
+      m = re.match('^\s*(\d+)\s+(\d+)\s+(.+)', l, re.DOTALL)
       assert m
-      procs.append(m.groups())
+      procs.append((int(m.group(1)), m.group(3), int(m.group(2))))
     logging.debug("ListProcesses(<predicate>)->[%i processes]" % len(procs))
     return procs
 
@@ -257,10 +258,10 @@ class CrOSInterface(object):
 
   def KillAllMatching(self, predicate):
     kills = ['kill', '-KILL']
-    for p in self.ListProcesses():
-      if predicate(p[1]):
-        logging.info('Killing %s', repr(p))
-        kills.append(p[0])
+    for pid, cmd, _ in self.ListProcesses():
+      if predicate(cmd):
+        logging.info('Killing %s, pid %d' % cmd, pid)
+        kills.append(pid)
     logging.debug("KillAllMatching(<predicate>)->%i" % (len(kills) - 2))
     if len(kills) > 2:
       self.RunCmdOnDevice(kills, quiet=True)
@@ -269,7 +270,7 @@ class CrOSInterface(object):
   def IsServiceRunning(self, service_name):
     stdout, stderr = self.RunCmdOnDevice([
         'status', service_name], quiet=True)
-    assert stderr == ''
+    assert stderr == '', stderr
     running = 'running, process' in stdout
     logging.debug("IsServiceRunning(%s)->%s" % (service_name, running))
     return running