Remove deadcode from depot_tools scripts

Removing some deadcode from depot_tools scripts. More follow-up CLs will
be made after this to remove more dead code.

R=sokcevic,gavinmak

Change-Id: Iad20e9e1737e49c1370248d32c6317cf2be63de4
Bug: 1475776
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/4811216
Commit-Queue: Aravind Vasudevan <aravindvasudev@google.com>
Reviewed-by: Gavin Mak <gavinmak@google.com>

fetch.py

@@ -24,10 +24,8 @@ import json
 import argparse
 import os
 import pipes
-import re
 import subprocess
 import sys
-import textwrap
 
 import git_common
 

gclient.py

@@ -128,12 +128,8 @@ class GNException(Exception):
   pass
 
 
-def ToGNString(value, allow_dicts = True):
-  """Returns a stringified GN equivalent of the Python value.
-
-  allow_dicts indicates if this function will allow converting dictionaries
-  to GN scopes. This is only possible at the top level, you can't nest a
-  GN scope in a list, so this should be set to False for recursive calls."""
+def ToGNString(value):
+  """Returns a stringified GN equivalent of the Python value."""
   if isinstance(value, str):
     if value.find('\n') >= 0:
       raise GNException("Trying to print a string with a newline in it.")

gclient_scm.py

@@ -1359,7 +1359,7 @@ class GitWrapper(SCMWrapper):
       os.path.isdir(os.path.join(g, "rebase-merge")) or
       os.path.isdir(os.path.join(g, "rebase-apply")))
 
-  def _CheckClean(self, revision, fixup=False):
+  def _CheckClean(self, revision):
     lockfile = os.path.join(self.checkout_path, ".git", "index.lock")
     if os.path.exists(lockfile):
       raise gclient_utils.Error(

git_map_branches.py

@@ -29,7 +29,6 @@ from __future__ import print_function
 import argparse
 import collections
 import metrics
-import os
 import subprocess2
 import sys
 

metrics.py

@@ -10,7 +10,6 @@ import functools
 import json
 import os
 import sys
-import tempfile
 import threading
 import time
 import traceback

tests/metrics_test.py

@@ -56,8 +56,6 @@ class MetricsCollectorTest(unittest.TestCase):
 
     # Patch the methods used to get the system information, so we have a known
     # environment.
-    mock.patch('metrics.tempfile.mkstemp',
-               lambda: (None, '/tmp/metrics.json')).start()
     mock.patch('metrics.time.time',
                TimeMock()).start()
     mock.patch('metrics.metrics_utils.get_python_version',