Revert of Use Clang's update.py --print-revision everywhere.

tools/clang/scripts/update.py

Index: tools/clang/scripts/update.py
diff --git a/tools/clang/scripts/update.py b/tools/clang/scripts/update.py
index 0789de57c967db5761d5bff7704a83b67899f5a7..06d241e80b8e77f01e33bffe034641304a7f348a 100755
--- a/tools/clang/scripts/update.py
+++ b/tools/clang/scripts/update.py
@@ -65,12 +65,6 @@
 
 def PrintRevision():
   """Print the current Clang revision."""
-  # gyp runs update.py --print-revision even when clang=1 isn't set.
-  # It won't use the value, but we must not error.
-  if not re.search(r'\b(clang|asan)=1', os.environ.get('GYP_DEFINES', '')):
-    print "0"
-    return
-
   # TODO(hans): This needs an update when we move to prebuilt Clang binaries.
   svn_info = subprocess.check_output(['svn', 'info', LLVM_DIR])
   m = re.search(r'Revision: (\d+)', svn_info)
@@ -88,6 +82,15 @@
     raise
 
   shutil.rmtree(dir, onerror=ChmodAndRetry)
+
+
+def ClobberChromiumBuildFiles():
+  """Clobber Chomium build files."""
+  print 'Clobbering Chromium build files...'
+  out_dir = os.path.join(CHROMIUM_DIR, 'out')
+  if os.path.isdir(out_dir):
+    RmTree(out_dir)
+    print 'Removed Chromium out dir: %s.' % (out_dir)
 
 
 def RunCommand(command, fail_hard=True):
@@ -222,6 +225,9 @@
     return 0
 
   AddCMakeToPath()
+  if args.clobber:
+    ClobberChromiumBuildFiles()
+
   # Reset the stamp file in case the build is unsuccessful.
   WriteStampFile('')
 
@@ -302,15 +308,12 @@
     # dup()ed sys.stdin is writable, try
     #   fd2 = os.dup(sys.stdin.fileno()); os.write(fd2, 'hi')
     # TODO: Fix gclient instead, http://crbug.com/95350
-    try:
-      stderr = os.fdopen(os.dup(sys.stdin.fileno()))
-    except:
-      stderr = sys.stderr
     return subprocess.call(
-        [os.path.join(os.path.dirname(__file__), 'update.sh')] + sys.argv[1:],
-        stderr=stderr)
+        [os.path.join(os.path.dirname(__file__), 'update.sh')] +  sys.argv[1:],
+        stderr=os.fdopen(os.dup(sys.stdin.fileno())))
 
   parser = argparse.ArgumentParser(description='Build Clang.')
+  parser.add_argument('--no-clobber', dest='clobber', action='store_false')
   parser.add_argument('--tools', nargs='*', default=['plugins'])
   # For now, this flag is only used for the non-Windows flow, but argparser gets
   # mad if it sees a flag it doesn't recognize.