Refactor fetch_benchmark_deps.py script to allow fetching all benchmark deps

tools/perf/fetch_benchmark_deps.py

Index: tools/perf/fetch_benchmark_deps.py
diff --git a/tools/perf/fetch_benchmark_deps.py b/tools/perf/fetch_benchmark_deps.py
index abde42f0ccfcee5a5c263f1ebdbdef473dad5a66..0a07d061a5a86c84be67d036b1c77af20e64cc19 100755
--- a/tools/perf/fetch_benchmark_deps.py
+++ b/tools/perf/fetch_benchmark_deps.py
@@ -5,9 +5,11 @@
 
 """This module fetches and prints the dependencies given a benchmark."""
 
+import argparse
 import os
 import sys
 
+from core import benchmark_finders
 from core import path_util
 
 path_util.AddPyUtilsToPath()
@@ -57,21 +59,7 @@ def _EnumerateDependencies(story_set):
   return [dep[prefix_len:] for dep in deps if dep]
 
 
-def _show_usage():
-  print ('Usage: %s benchmark_name\n'
-         'Fetch the dependencies of benchmark_name.' % sys.argv[0])
-
-
-def main(output=sys.stdout):
-  config = chromium_config.ChromiumConfig(
-      top_level_dir=path_util.GetPerfDir(),
-      benchmark_dirs=[os.path.join(path_util.GetPerfDir(), 'benchmarks')])
-
-  name = sys.argv[1]
-  benchmark = benchmark_runner.GetBenchmarkByName(name, config)
-  if not benchmark:
-    raise ValueError('No such benchmark: %s' % name)
-
+def FetchDepsForBenchmark(benchmark, output):
   # Download files according to specified benchmark.
   story_set = benchmark().CreateStorySet(None)
 
@@ -83,8 +71,35 @@ def main(output=sys.stdout):
     print >> output, dep
 
 
-if __name__ == '__main__':
-  if len(sys.argv) != 2 or sys.argv[1][0] == '-':
-    _show_usage()
+def main(args, output):
+  parser = argparse.ArgumentParser(
+         description='Fetch the dependencies of perf benchmark(s).')
+  parser.add_argument('benchmark_name', type=str, nargs='?')
+  parser.add_argument('--force', '-f',
+                      help=('Force fetching all the benchmarks when '
+                            'benchmark_name is not specified'),
+                      action='store_true', default=False)
+
+  options = parser.parse_args(args)
+
+  if options.benchmark_name:
+    config = chromium_config.ChromiumConfig(
+        top_level_dir=path_util.GetPerfDir(),
+        benchmark_dirs=[os.path.join(path_util.GetPerfDir(), 'benchmarks')])
+    benchmark = benchmark_runner.GetBenchmarkByName(
+        options.benchmark_name, config)
+    if not benchmark:
+      raise ValueError('No such benchmark: %s' % options.benchmark_name)
+    FetchDepsForBenchmark(benchmark, output)
   else:
-    main()
+    if not options.force:
+      raw_input(
+          'No benchmark name is specified. Fetching all benchmark deps. '
+          'Press enter to continue...')
+    for b in benchmark_finders.GetAllBenchmarks():
+      print >> output, ('Fetch dependencies for benchmark %s:'
+                        % benchmark.Name())
+      FetchDepsForBenchmark(b, output)
+
+if __name__ == '__main__':
+  main(sys.argv[1:], sys.stdout)