[sql] Histograms for I/O calls seen by browser VFS.

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 51f70d9eb846709efb26e7ed2e7b66aefa1fd933..1fd2e8f3c1ad07ade06ee38f68a613078fd3d747 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -67004,6 +67004,20 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   <summary>Version of pre-existing database at startup.</summary>
 </histogram>
 
+<histogram name="Sqlite.Vfs" units="bytes">
+  <owner>shess@chromium.org</owner>
+  <summary>
+    Buffer sizes passed to browser-process SQLite VFS functions.
+  </summary>
+</histogram>
+
+<histogram name="Sqlite.Vfs_Events" enum="SqliteVfsEvents">
+  <owner>shess@chromium.org</owner>
+  <summary>
+    I/O operations measured by browser-process SQLite VFS wrapper.
+  </summary>
+</histogram>
+
 <histogram name="Sqlite.Web.Error" enum="SqliteErrorCode">
   <obsolete>
     Moved to Sqlite.Error.Web in M-27.
@@ -110076,6 +110090,21 @@ from previous Chrome versions.
   <int value="5" label="DEPRECATION_RAZE_FAILED">Raze failed.</int>
 </enum>
 
+<enum name="SqliteVfsEvents" type="int">
+  <summary>I/O events from browser-process SQLite VFS wrapper.</summary>
+  <int value="0" label="VFS_OPEN">Calls to xOpen().</int>
+  <int value="1" label="VFS_DELETE">Calls to xDelete().</int>
+  <int value="2" label="VFS_ACCESS">Calls to xAccess().</int>
+  <int value="3" label="VFS_FULLPATHNAME">Calls to xFullPath().</int>
+  <int value="4" label="VFS_IO_CLOSE">Calls to xClose().</int>
+  <int value="5" label="VFS_IO_READ">Calls to xRead().</int>
+  <int value="6" label="VFS_IO_WRITE">Calls to xWrite().</int>
+  <int value="7" label="VFS_IO_TRUNCATE">Calls to xTruncate().</int>
+  <int value="8" label="VFS_IO_SYNC">Calls to xSync().</int>
+  <int value="9" label="VFS_IO_FILESIZE">Calls to xFileSize().</int>
+  <int value="10" label="VFS_IO_FETCH">Calls to xFetch().</int>
+</enum>
+
 <enum name="SRIResourceIntegrityMismatchEvent" type="int">
   <int value="0" label="CHECKING_FOR_INTEGRITY_MISMATCH"/>
   <int value="1" label="REFETCH_DUE_TO_INTEGRITY_MISMATCH"/>
@@ -121922,6 +121951,14 @@ from previous Chrome versions.
   <affected-histogram name="Sqlite.Version"/>
 </histogram_suffixes>
 
+<histogram_suffixes name="SqliteVfsOperations" separator="_">
+  <owner>shess@chromium.org</owner>
+  <suffix name="Fetch" label="fetch"/>
+  <suffix name="Read" label="read"/>
+  <suffix name="Write" label="write"/>
+  <affected-histogram name="Sqlite.Vfs"/>
+</histogram_suffixes>
+
 <histogram_suffixes name="SSLFalseStart">
   <obsolete>
     Removed 2011-06-01.