Reland "Make gclient ready for the Blink (DEPS to main project)"

scm.py

Index: scm.py
diff --git a/scm.py b/scm.py
index 9bc96bc8055832707a749d3b9d256766b5a43956..94b925e87d0abf14762462607221a88f51316214 100644
--- a/scm.py
+++ b/scm.py
@@ -443,6 +443,16 @@ class GIT(object):
       return False
 
   @staticmethod
+  def IsDirectoryVersioned(cwd, relative_dir):
+    """Checks whether the given |relative_dir| is part of cwd's repo."""
+    return bool(GIT.Capture(['ls-tree', 'HEAD', relative_dir], cwd=cwd))
+
+  @staticmethod
+  def CleanupDir(cwd, relative_dir):
+    """Cleans up untracked file inside |relative_dir|."""
+    return bool(GIT.Capture(['clean', '-df', relative_dir], cwd=cwd))
+
+  @staticmethod
   def GetGitSvnHeadRev(cwd):
     """Gets the most recently pulled git-svn revision."""
     try: