Fix start_xvfb return value; don't run xvfb for Android apptests.

The Chromium Mojo Android bot is failing apptests:
http://build.chromium.org/p/chromium.mojo/builders/Chromium%20Mojo%20Android

The return value was a mistake in my recent CL's latest patch set:
  https://codereview.chromium.org/1239563003

The platform filtering was a mistake in my recent CL:
  https://codereview.chromium.org/1230683002

BUG=NONE
TEST=Chromium Mojo Android bot passes apptests.
TBR=maruel@chromium.org,sky@chromium.org

Review URL: https://codereview.chromium.org/1224263005

Cr-Commit-Position: refs/heads/master@{#338979}

2 files changed, 4 insertions, 3 deletions

diff --git a/mojo/tools/mopy/gtest.py b/mojo/tools/mopy/gtest.py
index 887ae07..bb8306c 100644
--- a/mojo/tools/mopy/gtest.py
+++ b/mojo/tools/mopy/gtest.py
@@ -147,7 +147,8 @@ def _run_test_with_xvfb(config, shell, args, apptest):
   xvfb_proc = None
   openbox_proc = None
   env = os.environ.copy()
-  if '--gtest_list_tests' not in args and xvfb.should_start_xvfb(env):
+  if (config.target_os == Config.OS_LINUX and '--gtest_list_tests' not in args
+      and xvfb.should_start_xvfb(env)):
     (xvfb_proc, openbox_proc) = xvfb.start_xvfb(env, Paths(config).build_dir)
     if not xvfb_proc or not xvfb_proc.pid:
       raise Exception('Xvfb failed to start; aborting test run.')
@@ -197,7 +198,7 @@ def _run_test(config, shell, args, apptest, env, result):
   output = ''
   exception = ''
   try:
-    if (config.target_os != Config.OS_ANDROID):
+    if config.target_os != Config.OS_ANDROID:
       command = _build_command_line(config, args, apptest)
       process = subprocess.Popen(command, stdout=subprocess.PIPE,
                                  stderr=subprocess.PIPE, env=env)
diff --git a/testing/xvfb.py b/testing/xvfb.py
index c6e9ddf..67ef729 100755
--- a/testing/xvfb.py
+++ b/testing/xvfb.py
@@ -79,7 +79,7 @@ def start_xvfb(env, build_dir, xvfb_path='Xvfb', display=':9'):
       print 'Xvfb output:'
       for l in xvfb_proc.communicate()[0].splitlines():
         print '> %s' % l
-      return None
+      return (None, None)
 
     # Some ChromeOS tests need a window manager.
     openbox_proc = subprocess.Popen('openbox', stdout=subprocess.PIPE,