Fill is_chrome_signin_password field in the password entry pings.

components/password_manager/core/browser/password_reuse_detector.cc

Index: components/password_manager/core/browser/password_reuse_detector.cc
diff --git a/components/password_manager/core/browser/password_reuse_detector.cc b/components/password_manager/core/browser/password_reuse_detector.cc
index 5bf0abb361f9b1000de4c104cd6e484b568cc74c..0badf0bd3e47e9eefd531be1f964c5d26967a175 100644
--- a/components/password_manager/core/browser/password_reuse_detector.cc
+++ b/components/password_manager/core/browser/password_reuse_detector.cc
@@ -37,6 +37,8 @@ bool IsSuffix(const base::string16& str,
 
 }  // namespace
 
+const char kSyncPasswordDomain[] = "chrome_sync";

[Nathan Parker, 2017/06/07 22:16:06]

nit: how about making this not a valid hostname ("CHROME SYNC"?) to ensure no
one ever has a real domain w/ this same name?  

[Jialiu Lin, 2017/06/07 22:41:50]

Done.

+
 bool ReverseStringLess::operator()(const base::string16& lhs,
                                    const base::string16& rhs) const {
   return std::lexicographical_compare(lhs.rbegin(), lhs.rend(), rhs.rbegin(),
@@ -94,8 +96,8 @@ bool PasswordReuseDetector::CheckSyncPasswordReuse(
     base::StringPiece16 input_suffix(input.c_str() + i, input.size() - i);
     if (password_manager_util::Calculate37BitsOfSHA256Hash(input_suffix) ==
         sync_password_hash_.value()) {
-      consumer->OnReuseFound(input_suffix.as_string(), gaia_origin.host(), 1,
-                             0);
+      consumer->OnReuseFound(input_suffix.as_string(),
+                             std::string(kSyncPasswordDomain), 1, 0);
       return true;
     }
   }