Measure how often HTTPS credentials cannot be filled into HTTP forms.

tools/metrics/histograms/histograms.xml

Index: tools/metrics/histograms/histograms.xml
diff --git a/tools/metrics/histograms/histograms.xml b/tools/metrics/histograms/histograms.xml
index fb8f675c224d8e0873bb6e9543b644ce2e9abf0a..c140c100392c8d84834056b6d5ab25e214e6d185 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -50096,6 +50096,16 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   </summary>
 </histogram>
 
+<histogram name="PasswordManager.QueryingSuppressedAccountsFinished"
+    enum="Boolean">
+  <owner>engedy@chromium.org</owner>
+  <summary>
+    Records, for each password form seen by the password manager, whether the
+    PasswordStore responded quickly enough so that
+    PasswordManager.SuppressedAccount histogram samples could be computed.
+  </summary>
+</histogram>
+
 <histogram name="PasswordManager.SavePasswordPromptDisappearedQuickly"
     enum="Boolean">
   <obsolete>
@@ -50293,6 +50303,20 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   </summary>
 </histogram>
 
+<histogram name="PasswordManager.SuppressedAccount"
+    enum="PasswordManagerSuppressedAccountCrossActionsTaken">
+  <owner>engedy@chromium.org</owner>
+  <summary>
+    Records, for each password form seen by the password manager, whether there
+    were `suppressed` credentials, meaning stored credentials that were not
+    filled because they were for an origin that was similar to, but not exactly
+    (or PSL) matching the origin of the observed form (see the suffix
+    description for the possible classes of such near-matches).  If there were
+    such credentials, the histogram also records whether the username and
+    password of such suppressed credentials matched those submitted.
+  </summary>
+</histogram>
+
 <histogram name="PasswordManager.SyncCredentialFiltered"
     enum="CredentialFilteredType">
   <owner>gcasto@chromium.org</owner>
@@ -90810,6 +90834,21 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   <affected-histogram name="PasswordManager.SavePasswordPromptResponse"/>
 </histogram_suffixes>
 
+<histogram_suffixes name="PasswordManagerSuppressedAccountReason" separator=".">
+  <affected-histogram name="PasswordManager.SuppressedAccount.Generated"/>
+  <suffix name="HTTPSNotHTTP"
+      label="The credential was suppressed because it was for an HTTPS origin
+             whereas the observed form was for an HTTP origin."/>
+  <affected-histogram name="PasswordManager.SuppressedAccount.Manual"/>
+</histogram_suffixes>
+
+<histogram_suffixes name="PasswordManagerSuppressedAccountType" separator=".">
+  <suffix name="Generated" label="The password was originally auto-generated."/>
+  <suffix name="Manual"
+      label="The password was originally typed in by the user."/>
+  <affected-histogram name="PasswordManager.SuppressedAccount"/>
+</histogram_suffixes>
+
 <histogram_suffixes name="PasswordProtectionTrigger" separator=".">
   <suffix name="PasswordFieldOnFocus"
       label="Password protection triggered by password field on focus event."/>