[Telemetry] Fix a flake in android browser finder.

[Telemetry] Fix a flake in android browser finder.

Traceback (most recent call last):
  File "tools/perf/../telemetry/telemetry/decorators.py", line 50, in wrapper
    func(*args, **kwargs)
  File "/b/build/slave/Android_Tests/build/src/tools/perf/benchmarks/benchmark_unittest.py", line 51, in BenchmarkSmokeTest
    self.assertEqual(0, SinglePageBenchmark().Run(options),
  File "tools/perf/../telemetry/telemetry/benchmark.py", line 84, in Run
    results = page_runner.Run(test, ps, expectations, args)
  File "tools/perf/../telemetry/telemetry/page/page_runner.py", line 346, in Run
    possible_browser = browser_finder.FindBrowser(finder_options)
  File "tools/perf/../telemetry/telemetry/decorators.py", line 26, in Cacher
    cache[key] = obj(*args, **kwargs)
  File "tools/perf/../telemetry/telemetry/core/browser_finder.py", line 73, in FindBrowser
    curr_browsers = finder.FindAllAvailableBrowsers(options)
  File "tools/perf/../telemetry/telemetry/core/backends/chrome/android_browser_finder.py", line 214, in FindAllAvailableBrowsers
    pids  = [p.pid for p in psutil.process_iter() if 'adb' in p.name]
  File "/usr/lib/python2.7/dist-packages/psutil/__init__.py", line 161, in name
    cmdline = self.cmdline
  File "/usr/lib/python2.7/dist-packages/psutil/__init__.py", line 188, in cmdline
    return self._platform_impl.get_process_cmdline()
  File "/usr/lib/python2.7/dist-packages/psutil/_pslinux.py", line 327, in wrapper
    raise NoSuchProcess(self.pid, self._process_name)
NoSuchProcess: process no longer exists (pid=13764)

Observed here:
http://build.chromium.org/p/chromium.linux/builders/Android%20Tests/builds/14626/steps/telemetry_perf_unittests/logs/stdio

BUG=

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=284144

[dtu, 2014-07-18 03:00:51]

lgtm

[tonyg, 2014-07-18 04:23:55]

The CQ bit was checked by tonyg@chromium.org

[commit-bot: I haz the power, 2014-07-18 04:25:58]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/tonyg@chromium.org/394423002/40001

[commit-bot: I haz the power, 2014-07-18 05:43:54]

FYI, CQ is re-trying this CL (attempt #1).
The failing builders are:
  win_chromium_rel on tryserver.chromium
(http://build.chromium.org/p/tryserver.chromium/builders/win_chromium_rel/buil...)
  win_chromium_x64_rel on tryserver.chromium
(http://build.chromium.org/p/tryserver.chromium/builders/win_chromium_x64_rel/...)

[commit-bot: I haz the power, 2014-07-18 06:37:45]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2014-07-18 06:37:46]

Try jobs failed on following builders:
  win_chromium_x64_rel on tryserver.chromium
(http://build.chromium.org/p/tryserver.chromium/builders/win_chromium_x64_rel/...)

[tonyg, 2014-07-18 15:35:03]

The CQ bit was checked by tonyg@chromium.org

[commit-bot: I haz the power, 2014-07-18 15:36:51]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/tonyg@chromium.org/394423002/60001

[commit-bot: I haz the power, 2014-07-18 17:40:08]

Change committed as 284144

[tonyg, 2014-07-18 20:05:34]

A revert of this CL has been created in
https://codereview.chromium.org/407633002/ by tonyg@chromium.org.

The reason for reverting is: BUG=395228.