Make sharding_supervisor.py run InProcessBrowserTest.Empty

content/test/test_launcher.cc

Index: content/test/test_launcher.cc
===================================================================
--- content/test/test_launcher.cc	(revision 144098)
+++ content/test/test_launcher.cc	(working copy)
@@ -574,6 +574,8 @@
 
 const char kHelpFlag[]   = "help";
 
+const char kWarmupFlag[] = "warmup";
+
 TestLauncherDelegate::~TestLauncherDelegate() {
 }
 
@@ -635,15 +637,17 @@
   // from disk may be slow on a busy bot, and can easily exceed the default
   // timeout causing flaky test failures. Use an empty test that only starts
   // and closes a browser with a long timeout to avoid those problems.
-  // NOTE: we don't do this when specifying a filter because this slows down the
+  // NOTE: We don't do this when specifying a filter because this slows down the
   // common case of running one test locally, and also on trybots when sharding
   // as this one test runs ~200 times and wastes a few minutes.
-  if (!should_shard && !command_line->HasSwitch(kGTestFilterFlag)) {
+  bool warmup = command_line->HasSwitch(kWarmupFlag);
+  bool has_filter = command_line->HasSwitch(kGTestFilterFlag);
+  if (warmup || (!should_shard && !has_filter)) {
     exit_code = RunTest(launcher_delegate,
                         kEmptyTestName,
                         TestTimeouts::large_test_timeout_ms(),
                         NULL);
-    if (exit_code != 0)
+    if (exit_code != 0 || warmup)
       return exit_code;
   }