Log metrics for loading SQLiteChannelIDStore

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 07ea3437c777afe7928055acb7e3d351b2b33e69..29c4546927aacdadd9ffd3e94f1defddadfbb2ff 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -12739,6 +12739,15 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   <summary>Number of certs loaded from domain bound cert database.</summary>
 </histogram>
 
+<histogram name="DomainBoundCerts.DBLoadStatus"
+    enum="DomainBoundCerts.DBLoadStatus">
+  <owner>nharper@chromium.org</owner>
+  <summary>
+    The status of loading the Channel ID database from disk. This histogram
+    records why the database failed to load, or that it loaded successfully.
+  </summary>
+</histogram>
+
 <histogram name="DomainBoundCerts.DBLoadTime" units="ms">
   <owner>mattm@chromium.org</owner>
   <summary>Time spent loading domain bound cert database.</summary>
@@ -12754,6 +12763,14 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   </summary>
 </histogram>
 
+<histogram name="DomainBoundCerts.DBVersion">
+  <owner>nharper@chromium.org</owner>
+  <summary>
+    The version number of the Channel ID database (before any migrations are
+    run).
+  </summary>
+</histogram>
+
 <histogram name="DomainBoundCerts.GenerateCertTime" units="ms">
   <obsolete>
     Removed 4/2017.
@@ -88637,6 +88654,17 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   <int value="2" label="Same Site Different Scheme Script"/>
 </enum>
 
+<enum name="DomainBoundCerts.DBLoadStatus" type="int">
+  <int value="0" label="Database path doesn't exist and couldn't be created"/>
+  <int value="1" label="Unable to open database"/>
+  <int value="2" label="Failed to migrate db to current version"/>
+  <int value="3" label="Invalid SELECT statement to load db"/>
+  <int value="4" label="Successfully created new db"/>
+  <int value="5" label="Successfully loaded existing db"/>
+  <int value="6"
+      label="Loaded existing db, but failed to load one or more keys"/>
+</enum>
+
 <enum name="DomainBoundCerts.GetCertResult" type="int">
   <int value="0" label="SYNC_SUCCESS"/>
   <int value="1" label="ASYNC_SUCCESS"/>