Add a new 'format-webkitpy' command that will reformat code to the style guide.

Tools/Scripts/webkitpy/common/system/executive.py

Index: Tools/Scripts/webkitpy/common/system/executive.py
diff --git a/Tools/Scripts/webkitpy/common/system/executive.py b/Tools/Scripts/webkitpy/common/system/executive.py
index 4f2223efa9e2da4d00d5167c77a3fc7c0a328163..f52db0a1a4b25b76dc512d4861f0adb0c6722af9 100644
--- a/Tools/Scripts/webkitpy/common/system/executive.py
+++ b/Tools/Scripts/webkitpy/common/system/executive.py
@@ -471,14 +471,17 @@ class Executive(object):
     def run_in_parallel(self, command_lines_and_cwds, processes=None):
         """Runs a list of (cmd_line list, cwd string) tuples in parallel and returns a list of (retcode, stdout, stderr) tuples."""
         assert len(command_lines_and_cwds)
+        return self.map(_run_command_thunk, command_lines_and_cwds, processes)
 
-        if sys.platform in ('cygwin', 'win32'):
-            return map(_run_command_thunk, command_lines_and_cwds)
-        pool = multiprocessing.Pool(processes=processes)
-        results = pool.map(_run_command_thunk, command_lines_and_cwds)
-        pool.close()
-        pool.join()
-        return results
+    def map(self, thunk, arglist, processes=None):
+        if sys.platform in ('cygwin', 'win32') or len(arglist) == 1:
+            return map(thunk, arglist)
+        pool = multiprocessing.Pool(processes=(processes or multiprocessing.cpu_count()))
+        try:
+            return pool.map(thunk, arglist)
+        finally:
+            pool.close()
+            pool.join()
 
 
 def _run_command_thunk(cmd_line_and_cwd):