[SimpleCache] Track some SimpleCache size stats on initialization

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 0e96895f27242bb97cb1ad2ac006fa7f048d365d..85c50c0962a25979d02b3ced9a14caaa26b7ad9f 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -56249,6 +56249,13 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   </summary>
 </histogram>
 
+<histogram name="SimpleCache.CacheSizeOnInit" units="KB">
+  <owner>jkarlin@chromium.org</owner>
+  <summary>
+    The size of the cache at the time that the index has finished initializing.
+  </summary>
+</histogram>
+
 <histogram name="SimpleCache.CheckCRCResult" enum="CheckCRCResult">
   <owner>gavinp@chromium.org</owner>
   <summary>
@@ -56534,6 +56541,14 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   </summary>
 </histogram>
 
+<histogram name="SimpleCache.IndexNumEntriesOnInit">

[rkaplow, 2016/09/26 14:00:42]

shuold still have a unit, like "entries" or something

[jkarlin, 2016/09/26 15:42:53]

Done.

+  <owner>jkarlin@chromium.org</owner>
+  <summary>
+    The number of entries in the index at the time that the index has finished
+    initializing.
+  </summary>
+</histogram>
+
 <histogram name="SimpleCache.IndexNumEntriesOnWrite">
   <owner>gavinp@chromium.org</owner>
   <summary>The number of entries written to the index on a flush.</summary>
@@ -56649,6 +56664,14 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   </summary>
 </histogram>
 
+<histogram name="SimpleCache.MaxCacheSizeOnInit" units="KB">
+  <owner>jkarlin@chromium.org</owner>
+  <summary>
+    The maximum allowed size of the cache at the time that the index has
+    finished initializing.
+  </summary>
+</histogram>
+
 <histogram name="SimpleCache.OpenEntryIndexState"
     enum="SimpleCacheOpenEntryIndexState">
   <owner>gavinp@chromium.org</owner>
@@ -56657,6 +56680,15 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   </summary>
 </histogram>
 
+<histogram name="SimpleCache.PercentFullOnInit" units="%">
+  <owner>jkarlin@chromium.org</owner>
+  <summary>
+    The fullness (in percent) of the cache at the time that the index has
+    finished initializing. The percentage is calculated as (cache_size * 100) /
+    max_cache_size.
+  </summary>
+</histogram>
+
 <histogram name="SimpleCache.ReadIsParallelizable"
     enum="SimpleCacheReadParallelizable">
   <owner>gavinp@chromium.org</owner>
@@ -100103,6 +100135,7 @@ To add a new entry, add it with any value and run test to compute valid value.
       label="Collected from the HTML5 Application Cache instance."/>
   <suffix name="Http" label="Collected from the HTTP Cache instance."/>
   <suffix name="Media" label="Collected from the Media Cache instance."/>
+  <affected-histogram name="SimpleCache.CacheSizeOnInit"/>
   <affected-histogram name="SimpleCache.CheckCRCResult"/>
   <affected-histogram name="SimpleCache.CreationToIndex"/>
   <affected-histogram name="SimpleCache.CreationToIndexFail"/>
@@ -100141,6 +100174,7 @@ To add a new entry, add it with any value and run test to compute valid value.
   <affected-histogram name="SimpleCache.IndexInitializationWaiters"/>
   <affected-histogram name="SimpleCache.IndexInitializeMethod"/>
   <affected-histogram name="SimpleCache.IndexLoadTime"/>
+  <affected-histogram name="SimpleCache.IndexNumEntriesOnInit"/>
   <affected-histogram name="SimpleCache.IndexNumEntriesOnWrite"/>
   <affected-histogram name="SimpleCache.IndexRestoreTime"/>
   <affected-histogram name="SimpleCache.IndexWriteInterval.Background"/>
@@ -100152,7 +100186,9 @@ To add a new entry, add it with any value and run test to compute valid value.
   <affected-histogram name="SimpleCache.KeyMatchedOnOpen"/>
   <affected-histogram name="SimpleCache.LastClusterLossPercent"/>
   <affected-histogram name="SimpleCache.LastClusterSize"/>
+  <affected-histogram name="SimpleCache.MaxCacheSizeOnInit"/>
   <affected-histogram name="SimpleCache.OpenEntryIndexState"/>
+  <affected-histogram name="SimpleCache.PercentFullOnInit"/>
   <affected-histogram name="SimpleCache.ReadIsParallelizable"/>
   <affected-histogram name="SimpleCache.ReadResult"/>
   <affected-histogram name="SimpleCache.StaleIndexExtraEntryCount"/>