Add verbose option to misc.ChDir

BUG=skia:
R=rmistry@google.com

Review URL: https://codereview.chromium.org/349973004

py/utils/misc.py

diff --git a/py/utils/misc.py b/py/utils/misc.py
index a61527e..a1bec6a 100644
--- a/py/utils/misc.py
+++ b/py/utils/misc.py
@@ -67,14 +67,16 @@
 class ChDir(object):
   """Enter and exit the given directory appropriately."""
 
-  def __init__(self, directory):
+  def __init__(self, directory, verbose=True):
     """Instantiate the ChDir.
 
     Args:
         directory: string; the directory to enter.
+        verbose: bool; whether or not to print the directory changes.
     """
     self._destination = directory
     self._origin = None
+    self._verbose = verbose
 
   def __enter__(self):
     """Change to the destination directory.
@@ -82,12 +84,14 @@
     Does not check whether the directory exists.
     """
     self._origin = os.getcwd()
-    print 'chdir %s' % self._destination
+    if self._verbose:
+      print 'chdir %s' % self._destination
     os.chdir(self._destination)
 
   def __exit__(self, *args):
     """Change back to the original directory."""
-    print 'chdir %s' % self._origin
+    if self._verbose:
+      print 'chdir %s' % self._origin
     os.chdir(self._origin)