Revert the revert. (its time to sign MR1)

Revert "Waiting till post MR0 - this impacts signing tools for MR0."

This reverts commit a7b5c4a7dc77a0896d6314828b9ce85f82d103e8.

Bug: 11334314
Change-Id: I89f8996161e4258b80bf2d0bc7817f0e8e32df13
diff --git a/tools/releasetools/check_target_files_signatures b/tools/releasetools/check_target_files_signatures
index ae372ba..45d30a6 100755
--- a/tools/releasetools/check_target_files_signatures
+++ b/tools/releasetools/check_target_files_signatures
@@ -135,7 +135,7 @@
 
     for i in to_load:
       f = open(i)
-      cert = ParseCertificate(f.read())
+      cert = common.ParseCertificate(f.read())
       f.close()
       name, _ = os.path.splitext(i)
       name, _ = os.path.splitext(name)
@@ -144,21 +144,6 @@
 ALL_CERTS = CertDB()
 
 
-def ParseCertificate(data):
-  """Parse a PEM-format certificate."""
-  cert = []
-  save = False
-  for line in data.split("\n"):
-    if "--END CERTIFICATE--" in line:
-      break
-    if save:
-      cert.append(line)
-    if "--BEGIN CERTIFICATE--" in line:
-      save = True
-  cert = "".join(cert).decode('base64')
-  return cert
-
-
 def CertFromPKCS7(data, filename):
   """Read the cert out of a PKCS#7-format file (which is what is
   stored in a signed .apk)."""
@@ -175,7 +160,7 @@
       AddProblem("error reading cert:\n" + err)
       return None
 
-    cert = ParseCertificate(out)
+    cert = common.ParseCertificate(out)
     if not cert:
       AddProblem("error parsing cert output")
       return None