IndexedDB: Added timing histograms.

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 d51e0645a245845bb7e73e3b994bdfcbdbbf0277..07705fd34fda0673f201784f9e2fa160c01d1c41 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -35746,6 +35746,38 @@ Therefore, the affected-histogram name has to have at least one dot in it.
   </summary>
 </histogram>
 
+<histogram name="WebCore.IndexedDB.LevelDB.OpenTime" units="milliseconds">
+  <owner>cmumford@chromium.org</owner>
+  <summary>
+    The time that it takes to open IndexedDB's LevelDB backing store.
+  </summary>
+</histogram>
+
+<histogram name="WebCore.IndexedDB.LevelDB.PutTime" units="milliseconds">
+  <owner>cmumford@chromium.org</owner>
+  <summary>
+    The time that it takes to write the data IndexedDB to the LevelDB backing
+    store for a put operation.
+  </summary>
+</histogram>
+
+<histogram name="WebCore.IndexedDB.LevelDB.Transaction.CommitTime"
+    units="milliseconds">
+  <owner>cmumford@chromium.org</owner>
+  <summary>
+    The time that it takes to commit an IndexedDB transaction to its LevelDB
+    backing store.
+  </summary>
+</histogram>
+
+<histogram name="WebCore.IndexedDB.LevelDB.WriteTime" units="milliseconds">
+  <owner>cmumford@chromium.org</owner>
+  <summary>
+    The time that it takes to write data to an IndexedDB's LevelDB backing
+    store.
+  </summary>
+</histogram>
+
 <histogram name="WebCore.IndexedDB.LevelDBOpenErrors" enum="LevelDBErrorTypes">
   <owner>dgrogan@chromium.org</owner>
   <summary>