Fix webkit-patch --help.

I believe that after http://crrev.com/2276713002, invoking webkit-patch
with --help rather than help was broken.

When `webkit-patch help` is invoked, the codepath that's used goes through
the execute method of HelpCommand, and the _tool attribute is set, so it
worked.

But when --help is passed, a different codepath is used, that goes through
optparse which directly uses HelpCommand.help_epilog and the _tool attribute
was never set.

This CL fixes this case by setting the _tool attribute in the constructor
of HelpCommand.

Review-Url: https://codereview.chromium.org/2385373003
Cr-Commit-Position: refs/heads/master@{#423017}

third_party/WebKit/Tools/Scripts/webkitpy/tool/commands/help_command.py

@@ -36,7 +36,7 @@ class HelpCommand(Command):
     help_text = "Display information about this program or its subcommands"
     argument_names = "[COMMAND]"
 
-    def __init__(self):
+    def __init__(self, tool=None):
         options = [
             optparse.make_option(
                 "-a",
@@ -46,11 +46,12 @@ class HelpCommand(Command):
                 help="Print all available commands"),
         ]
         super(HelpCommand, self).__init__(options)
-        # A hack used to pass --all-commands to _help_epilog even though it's called by the OptionParser.
+        # A hack used to pass --all-commands to help_epilog even though it's called by the OptionParser.
         self.show_all_commands = False
-        self._tool = None
+        # self._tool is used in help_epilog, so it's passed in the initializer rather than set in the execute method.
+        self._tool = tool
 
-    def _help_epilog(self):
+    def help_epilog(self):
         # Only show commands which are relevant to this checkout's SCM system.  Might this be confusing to some users?
         if self.show_all_commands:
             epilog = "All %prog commands:\n"
@@ -73,7 +74,6 @@ class HelpCommand(Command):
             self.option_parser.remove_option(option.get_opt_string())
 
     def execute(self, options, args, tool):
-        self._tool = tool
         if args:
             command = self._tool.command_by_name(args[0])
             if command:

third_party/WebKit/Tools/Scripts/webkitpy/tool/webkit_patch.py

@@ -96,7 +96,7 @@ class WebKitPatch(Host):
             RebaselineServer(),
             RebaselineTest(),
         ]
-        self.help_command = HelpCommand()
+        self.help_command = HelpCommand(tool=self)
         self.commands.append(self.help_command)
 
     def main(self, argv=None):
@@ -142,7 +142,7 @@ class WebKitPatch(Host):
     def _create_option_parser(self):
         usage = "Usage: %prog [options] COMMAND [ARGS]"
         name = optparse.OptionParser().get_prog_name()
-        return HelpPrintingOptionParser(epilog_method=self.help_command._help_epilog, prog=name, usage=usage)
+        return HelpPrintingOptionParser(epilog_method=self.help_command.help_epilog, prog=name, usage=usage)
 
     def _add_global_options(self, option_parser):
         global_options = self.global_options or []

third_party/WebKit/Tools/Scripts/webkitpy/tool/webkit_patch_unittest.py

@@ -30,7 +30,7 @@ class WebKitPatchTest(unittest.TestCase):
         self.assertEqual(tool.command_by_name('help').name, 'help')
         self.assertIsNone(tool.command_by_name('non-existent'))
 
-    def test_help(self):
+    def test_help_command(self):
         oc = OutputCapture()
         oc.capture_output()
         tool = WebKitPatch('path')
@@ -39,3 +39,17 @@ class WebKitPatchTest(unittest.TestCase):
         self.assertTrue(out.startswith('Usage: '))
         self.assertEqual('', err)
         self.assertEqual('', logs)
+
+    def test_help_argument(self):
+        oc = OutputCapture()
+        oc.capture_output()
+        tool = WebKitPatch('path')
+        try:
+            tool.main(['tool', '--help'])
+        except SystemExit:
+            pass  # optparse calls sys.exit after showing help.
+        finally:
+            out, err, logs = oc.restore_output()
+        self.assertTrue(out.startswith('Usage: '))
+        self.assertEqual('', err)
+        self.assertEqual('', logs)