Add missing history entry for primary token missing when loading

The histogram that counts token state transitions was not correctly
tracking the cases when Chrome fails to load a token for the primary
account. This CL adds this entry to the histogram. This should allow us
to understand to what extent Chrome fails to load tokens from disk.

Bug: NONE
Change-Id: I6237d5090984e0244a6203d60f2c319072b73555
Reviewed-on: https://chromium-review.googlesource.com/c/1278731
Commit-Queue: Mihai Sardarescu <msarda@chromium.org>
Reviewed-by: David Roger <droger@chromium.org>
Cr-Commit-Position: refs/heads/master@{#599207}

chrome/browser/signin/mutable_profile_oauth2_token_service_delegate.cc

@@ -51,6 +51,7 @@ enum class TokenStateTransition {
   // Load events.
   kLoadRegular,
   kLoadInvalid,
+  kLoadInvalidNoTokenForPrimaryAccount,
 
   kCount
 };
@@ -556,6 +557,8 @@ void MutableProfileOAuth2TokenServiceDelegate::OnWebDataServiceRequestDone(
                      GoogleServiceAuthError::FromInvalidGaiaCredentialsReason(
                          GoogleServiceAuthError::InvalidGaiaCredentialsReason::
                              CREDENTIALS_MISSING));
+    RecordTokenStateTransition(
+        TokenStateTransition::kLoadInvalidNoTokenForPrimaryAccount);
     FireRefreshTokenAvailable(loading_primary_account_id_);
   }
 

tools/metrics/histograms/enums.xml

@@ -45644,6 +45644,7 @@ Called by update_net_trust_anchors.py.-->
   <int value="6" label="Regular to None"/>
   <int value="7" label="Load Regular"/>
   <int value="8" label="Load Invalid"/>
+  <int value="9" label="Load Invalid (no token for primary)"/>
 </enum>
 
 <enum name="SigninTokenTableReadTokenFromDBResult">