Deprecate CredentialRequestOptions.unmediated in favor mediation enum

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 1382872432b3b8c1226f1e9e1794c13eb7cae33f..78a364942d0f1f560c32c2a4c951f8737f006d78 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -49634,6 +49634,10 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
 </histogram>
 
 <histogram name="PasswordManager.GetMediated" enum="CredentialManagerGetResult">
+  <obsolete>
+    Deprecated as of 05/2017. This metric has been replaced by
+    PasswordManager.MediationOptional.
+  </obsolete>
   <owner>vasilii@chromium.org</owner>
   <summary>
     Tracks result of navigator.credentials.get() with unmediated=false. That is
@@ -49643,6 +49647,10 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
 
 <histogram name="PasswordManager.GetUnmediated"
     enum="CredentialManagerGetResult">
+  <obsolete>
+    Deprecated as of 05/2017. This metric has been replaced by
+    PasswordManager.MediationSilent.
+  </obsolete>
   <owner>vasilii@chromium.org</owner>
   <summary>
     Tracks result of navigator.credentials.get() with unmediated=true. That is
@@ -49768,6 +49776,37 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   <summary>An error on LoginDatabase initialization.</summary>
 </histogram>
 
+<histogram name="PasswordManager.MediationOptional"
+    enum="CredentialManagerGetResult">
+  <owner>jdoerrie@chromium.org</owner>
+  <owner>vasilii@chromium.org</owner>
+  <summary>
+    Tracks result of navigator.credentials.get() with
+    mediation=&quot;optional&quot;. That is the result of account chooser.
+  </summary>
+</histogram>
+
+<histogram name="PasswordManager.MediationRequired"
+    enum="CredentialManagerGetResult">
+  <owner>jdoerrie@chromium.org</owner>
+  <owner>vasilii@chromium.org</owner>
+  <summary>
+    Tracks result of navigator.credentials.get() with
+    mediation=&quot;required&quot;. That is the result of forced account
+    chooser.
+  </summary>
+</histogram>
+
+<histogram name="PasswordManager.MediationSilent"
+    enum="CredentialManagerGetResult">
+  <owner>jdoerrie@chromium.org</owner>
+  <owner>vasilii@chromium.org</owner>
+  <summary>
+    Tracks result of navigator.credentials.get() with
+    mediation=&quot;silent&quot;. That is the result of auto sign-in.
+  </summary>
+</histogram>
+
 <histogram name="PasswordManager.MultiAccountPasswordUpdateAction"
     enum="MultiAccountUpdateBubbleUserAction">
   <owner>dvadym@chromium.org</owner>