Work around --profiler=perf failure with recent linux perf.

Looks like perf --call-graph now requires an argument
in the most recent perf binary.  That's probably a bug
in perf, but moving back to -g for now.

I tried running the telemetry tests, but gave up
after several minutes of gorilla videos stealing focus from my browser.

I found
src/tools/telemetry/telemetry/core/platform/profiler/perf_profiler_unittest.py
but it didn't seem to attempt to test this code
(or have a recommended way for instantiating this kind of
PerfProfiler so I could call this instance method) so I
gave up on testing.

BUG=366928

Review URL: https://codereview.chromium.org/257463007

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@266272 0039d316-1c4b-4281-b951-d872f2087c98

tools/telemetry/telemetry/core/platform/profiler/perf_profiler.py

@@ -41,8 +41,10 @@ class _SingleProcessPerfProfiler(object):
           'mkdir -p ' + os.path.dirname(self._device_output_file))
     else:
       cmd_prefix = ['perf']
+    # In perf 3.13 --call-graph requires an argument, so use
+    # the -g short-hand which does not.
     self._proc = subprocess.Popen(cmd_prefix +
-        ['record', '--call-graph',
+        ['record', '-g',
          '--pid', str(pid), '--output', output_file],
         stdout=self._tmp_output_file, stderr=subprocess.STDOUT)