Make sharding_supervisor.py run InProcessBrowserTest.Empty

tools/sharding_supervisor/sharding_supervisor.py

 #!/usr/bin/env python
 # Copyright (c) 2012 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 """Shards a given test suite and runs the shards in parallel.
 
 ShardingSupervisor is called to process the command line options and creates
 the specified number of worker threads. These threads then run each shard of
 the test in a separate process and report on the results. When all the shards
@@ skipping 579 matching lines @@
   num_cores = DetectNumCores()
 
   if options.shards_per_core < 1:
     parser.error("You must have at least 1 shard per core!")
   num_shards_to_run = num_cores * options.shards_per_core
 
   if options.runs_per_core < 1:
     parser.error("You must have at least 1 run per core!")
   num_runs = num_cores * options.runs_per_core
 
+  test = args[0]
   gtest_args = ["--gtest_color=%s" % {
       True: "yes", False: "no"}[options.color]] + args[1:]
 
   if options.original_order:
     options.prefix = True
 
   # TODO(charleslee): for backwards compatibility with buildbot's log_parser
   if options.reorder:
     options.original_order = False
     options.prefix = True
 
   if options.random_seed:
     seed = random.randint(1, 99999)
     gtest_args.extend(["--gtest_shuffle", "--gtest_random_seed=%i" % seed])
 
   if options.retry_failed:
     if options.retry_percent < 0 or options.retry_percent > 100:
       parser.error("Retry percent must be an integer [0, 100]!")
   else:
     options.retry_percent = -1
 
   if options.runshard != None:
     # run a single shard and exit
     if (options.runshard < 0 or options.runshard >= num_shards_to_run):
       parser.error("Invalid shard number given parameters!")
     shard = RunShard(
-        args[0], num_shards_to_run, options.runshard, gtest_args, None, None)
+        test, num_shards_to_run, options.runshard, gtest_args, None, None)
     shard.communicate()
     return shard.poll()
 
+  # When running browser_tests, load the test binary into memory before running
+  # any tests. This is needed to prevent loading it from disk causing the first
+  # run tests to timeout flakily. See: http://crbug.com/124260
+  if "browser_tests" in test:
+    args = [test]
+    args.extend(gtest_args)
+    args.append("--warmup")
+    result = subprocess.call(args,
+                             bufsize=0,
+                             universal_newlines=True)
+    # If the test fails, don't run anything else.
+    if result != 0:
+      return result
+
   # shard and run the whole test
   ss = ShardingSupervisor(
-      args[0], num_shards_to_run, num_runs, options.color,
+      test, num_shards_to_run, num_runs, options.color,
       options.original_order, options.prefix, options.retry_percent,
       options.timeout, options.total_slaves, options.slave_index, gtest_args)
   return ss.ShardTest()
 
 
 if __name__ == "__main__":
   sys.exit(main())