Start the migration of passwords from the Keychain.

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 eb00594acbc0766b562c1d60d463d0ceeb409fb3..0a02c3dab713b05de8ab5d97dc134aa1a7f74f9b 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -27827,6 +27827,12 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   </summary>
 </histogram>
 
+<histogram name="PasswordManager.KeychainMigration.Status"
+    enum="KeychainMigrationStatus">
+  <owner>vasilii@chromium.org</owner>
+  <summary>The status of passwords migration from the Keychain.</summary>
+</histogram>
+
 <histogram name="PasswordManager.KWalletDeserializationStatus"
     enum="BooleanSuccess">
   <owner>gcasto@chromium.org</owner>
@@ -58772,6 +58778,13 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   <int value="2" label="Keyboard was hidden by the user."/>
 </enum>
 
+<enum name="KeychainMigrationStatus" type="int">
+  <int value="0" label="Migration hasn't started."/>
+  <int value="1" label="Migration succeeded."/>
+  <int value="2" label="Migation failed once."/>
+  <int value="3" label="Migration failed twice."/>
+</enum>
+
 <enum name="LanguageCode" type="int">
   <summary>ISO 639 Language Codes.</summary>
   <int value="24929" label="Afar"/>