Added common git 'checkout' function

Added common git 'checkout' function

Replaced multiple various invocations of 'git checkout' with calls to a common
checkout function.

BUG=373504
TEST=localtest
R=agable@chromium.org, iannucci@chromium.org

Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=279207

[dnj, 2014-06-10 20:54:20]

PTAL

[dnj, 2014-06-16 15:38:00]

ping (+mmoss, +nodir)

[dnj, 2014-06-16 18:33:02]

+maruel, since he knows 'gclient'.

[dnj, 2014-06-23 20:38:47]

PING (maruel@, I'd like you to be primary reviewer since the others don't have
time right now. Please let me know if you don't either!)

[iannucci, 2014-06-23 21:01:11]

lgtm

[dnj, 2014-06-23 22:30:25]

The CQ bit was checked by dnj@chromium.org

[commit-bot: I haz the power, 2014-06-23 22:31:00]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/dnj@chromium.org/326153003/1

[commit-bot: I haz the power, 2014-06-23 22:31:05]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2014-06-23 22:31:06]

Failed to apply patch for depot_tools/gclient_scm.py:
While running patch -p1 --forward --force --no-backup-if-mismatch;
  patching file depot_tools/gclient_scm.py
  Hunk #1 succeeded at 395 (offset 16 lines).
  Hunk #2 FAILED at 479.
  Hunk #3 succeeded at 842 (offset 21 lines).
  Hunk #4 succeeded at 1015 (offset 21 lines).
  1 out of 4 hunks FAILED -- saving rejects to file
depot_tools/gclient_scm.py.rej

Patch:       depot_tools/gclient_scm.py
Index: gclient_scm.py
diff --git depot_tools/gclient_scm.py depot_tools/gclient_scm.py
index
26d96585cc667c0b7fd54a62372171e1c732b7e1..7a918b8b5f699d32b7e708eef2ce8bbef24cf278
100644
--- a/depot_tools/gclient_scm.py
+++ b/depot_tools/gclient_scm.py
@@ -379,7 +379,7 @@ class GitWrapper(SCMWrapper):
       if deps_revision and deps_revision.startswith('branch-heads/'):
         deps_branch = deps_revision.replace('branch-heads/', '')
         self._Capture(['branch', deps_branch, deps_revision])
-        self._Capture(['checkout', '--quiet', deps_branch])
+        self._Checkout(options, deps_branch, quiet=True)
       if file_list is not None:
         files = self._Capture(['ls-files']).splitlines()
         file_list.extend([os.path.join(self.checkout_path, f) for f in files])
@@ -479,7 +479,7 @@ class GitWrapper(SCMWrapper):
       if self._Capture(['rev-list', '-n', '1', 'HEAD']) == revision:
         self.Print('Up-to-date; skipping checkout.')
       else:
-        self._Capture(['checkout', '--quiet', '%s' % revision])
+        self._Checkout(options, revision, quiet=True)
       if not printed_path:
         self.Print('_____ %s%s' % (self.relpath, rev_str), timestamp=False)
     elif current_type == 'hash':
@@ -821,8 +821,7 @@ class GitWrapper(SCMWrapper):
         self.Print('_____ removing non-empty tmp dir %s' % tmp_dir)
       gclient_utils.rmtree(tmp_dir)
     self._UpdateBranchHeads(options, fetch=True)
-    self._Run(['checkout', '--quiet', revision.replace('refs/heads/', '')],
-              options)
+    self._Checkout(options, revision.replace('refs/heads/', ''), quiet=True)
     if self._GetCurrentBranch() is None:
       # Squelch git's very verbose detached HEAD warning and use our own
       self.Print(
@@ -995,6 +994,24 @@ class GitWrapper(SCMWrapper):
     env = scm.GIT.ApplyEnvVars(kwargs)
     return subprocess2.check_output(['git'] + args, env=env, **kwargs).strip()
 
+  def _Checkout(self, options, ref, quiet=None):
+    """Performs a 'git-checkout' operation.
+
+    Args:
+      options: The configured option set
+      ref: (str) The branch/commit to checkout
+      quiet: (bool/None) Whether or not the checkout shoud pass '--quiet'; if
+          'None', the behavior is inferred from 'options.verbose'.
+    Returns: (str) The output of the checkout operation
+    """
+    if quiet is None:
+      quiet = (not options.verbose)
+    checkout_args = ['checkout']
+    if quiet:
+      checkout_args.append('--quiet')
+    checkout_args.append(ref)
+    return self._Capture(checkout_args)
+
   def _UpdateBranchHeads(self, options, fetch=False):
     """Adds, and optionally fetches, "branch-heads" refspecs if requested."""
     if hasattr(options, 'with_branch_heads') and options.with_branch_heads:

[dnj, 2014-06-23 22:40:17]

The CQ bit was checked by dnj@chromium.org

[commit-bot: I haz the power, 2014-06-23 22:41:02]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/dnj@chromium.org/326153003/20001

[commit-bot: I haz the power, 2014-06-23 22:42:53]

Change committed as 279207