Updated comment in tab_switching.cc to replect that Tab-switching test in...

Updated comment in tab_switching.cc to replect that Tab-switching test in buildbot was outputting 0 because it was missing command line flag -log-level=0. log-level decides the amount of output in the log file, and histograms come under log-level 0. The default was 1, which meant that histograms were not logged - hence the results always showed 0.

BUG=www.crbug.com/22965
TEST=none
Review URL: http://codereview.chromium.org/239006

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@27150 0039d316-1c4b-4281-b951-d872f2087c98

chrome/test/tab_switching/tab_switching_test.cc

@@ -25,7 +25,7 @@ namespace {
 // time taken for each switch. It then prints out the times on the console,
 // with the aim that the page cycler parser can interpret these numbers to
 // draw graphs for page cycler Tab Switching Performance.
-// Usage Flags: -enable-logging -dump-histograms-on-exit
+// Usage Flags: -enable-logging -dump-histograms-on-exit -log-level=0
 class TabSwitchingUITest : public UITest {
  public:
   TabSwitchingUITest() {