Add --quiet option.

This is need, e.g., to suppress logging message for 'exists'.

TBR=agable@chromium.org,hinoka@chromium.org
BUG=

Review URL: https://codereview.chromium.org/299163002

git-svn-id: svn://svn.chromium.org/chrome/trunk/tools/depot_tools@272450 0039d316-1c4b-4281-b951-d872f2087c98

git_cache.py

@@ -496,11 +496,18 @@ class OptionParser(optparse.OptionParser):
     optparse.OptionParser.__init__(self, *args, prog='git cache', **kwargs)
     self.add_option('-c', '--cache-dir',
                     help='Path to the directory containing the cache')
-    self.add_option('-v', '--verbose', action='count', default=0,
+    self.add_option('-v', '--verbose', action='count', default=1,
                     help='Increase verbosity (can be passed multiple times)')
+    self.add_option('-q', '--quiet', action='store_true',
+                    help='Suppress all extraneous output')
 
   def parse_args(self, args=None, values=None):
     options, args = optparse.OptionParser.parse_args(self, args, values)
+    if options.quiet:
+      options.verbose = 0
+
+    levels = [logging.ERROR, logging.WARNING, logging.INFO, logging.DEBUG]
+    logging.basicConfig(level=levels[min(options.verbose, len(levels) - 1)])
 
     try:
       global_cache_dir = Mirror.GetCachePath()
@@ -513,9 +520,6 @@ class OptionParser(optparse.OptionParser):
         logging.warn('Overriding globally-configured cache directory.')
       Mirror.SetCachePath(options.cache_dir)
 
-    levels = [logging.WARNING, logging.INFO, logging.DEBUG]
-    logging.basicConfig(level=levels[min(options.verbose, len(levels) - 1)])
-
     return options, args