Extracting GetBooleanGnArg from coverage_report.py

Change-Id: I5475b37aad69361e2e7fae4ce69faf011e3b5c40
Reviewed-on: https://pdfium-review.googlesource.com/10030
Reviewed-by: Ryan Harrison <rharrison@chromium.org>
Commit-Queue: Henrique Nakashima <hnakashima@chromium.org>
diff --git a/testing/tools/common.py b/testing/tools/common.py
index c3bc218..737169f 100755
--- a/testing/tools/common.py
+++ b/testing/tools/common.py
@@ -99,12 +99,14 @@
     return result
 
 
-def GetBooleanGnArg(arg_name, build_dir):
-    '''Extract the value of a boolean flag in args.gn'''
-    cwd = os.getcwd()
-    os.chdir(build_dir)
-    gn_args_output = subprocess.check_output(
-        ['gn', 'args', '.', '--list=%s' % arg_name, '--short'])
-    os.chdir(cwd)
-    arg_match_output = re.search('%s = (.*)' % arg_name, gn_args_output).group(1)
-    return arg_match_output == 'true'
+def GetBooleanGnArg(arg_name, build_dir, verbose=False):
+  '''Extract the value of a boolean flag in args.gn'''
+  cwd = os.getcwd()
+  os.chdir(build_dir)
+  gn_args_output = subprocess.check_output(
+      ['gn', 'args', '.', '--list=%s' % arg_name, '--short'])
+  os.chdir(cwd)
+  arg_match_output = re.search('%s = (.*)' % arg_name, gn_args_output).group(1)
+  if verbose:
+    print >> sys.stderr, "Found '%s' for value of %s" % (arg_match_output, arg)
+  return arg_match_output == 'true'