Create a field trial to test if we can detect good QPC implementations.

tools/metrics/histograms/histograms.xml

 <!--
 Copyright 2013 The Chromium Authors. All rights reserved.
 Use of this source code is governed by a BSD-style license that can be
 found in the LICENSE file.
 -->
 
 <!--
 This file is used to generate a comprehensive list of Chrome histograms along
 with a detailed description for each histogram.
 
@@ skipping 6223 matching lines @@
     Error classes returned by LevelDB when it failed to open a database.
   </summary>
 </histogram>
 
 <histogram name="WebCore.IndexedDB.LevelDBWriteErrors" enum="LevelDBErrorTypes">
   <summary>
     Error classes returned by LevelDB when it failed to write to a database.
   </summary>
 </histogram>
 
+<histogram name="WinTimeTicks.FailedToChangeCores" enum="WindowsVersion">
+  <summary>
+    Incremented each time the TimeTicks field trial runs on a machine with
+    multiple cores, but failed to change thread affinity. Broken down by Windows
+    version.
+  </summary>
+</histogram>
+
+<histogram name="WinTimeTicks.MinResolutionNanoseconds" units="nanoseconds">
+  <summary>
+    The smallest non-zero delta reported by subsequent calls to
+    QueryPerformanceCounter.
+  </summary>
+</histogram>
+
+<histogram name="WinTimeTicks.NonStopTsc">
+  <summary>
+    True if the CPU's time stamp counter ticks at a constant rate regardless of
+    CPU frequency.
+  </summary>
+</histogram>
+
+<histogram name="WinTimeTicks.TickedBackwards" enum="WindowsVersion">
+  <summary>
+    The number of times the TimeTicks field trial failed because
+    QueryPerformanceCounter ticked backwards. Broken down by Windows version.
+  </summary>
+</histogram>
+
+<histogram name="WinTimeTicks.VersionSuccessful" enum="WindowsVersion">
+  <summary>
+    The number of times the TimeTicks field trial succeeded. Broken down by
+    Windows version.
+  </summary>
+</histogram>
+
+<histogram name="WinTimeTicks.VersionTotal" enum="WindowsVersion">
+  <summary>
+    The number of times the TimeTicks field trial ran for comparison with
+    WinTimeTicks.VersionSuccess. Broken down by Windows version.
+  </summary>
+</histogram>
+
 </histograms>
 
 <!-- Enum types -->
 
 <enums>
 
 <enum name="Abandoned" type="int">
   <int value="0" label="Finished"/>
   <int value="1" label="Abandoned"/>
 </enum>
@@ skipping 3457 matching lines @@
   <int value="45" label="kReasonCodeCipherSuiteNotSupported"/>
 </enum>
 
 <enum name="WiFiStatusType" type="int">
   <int value="0" label="kStatusCodeTypeByAp"/>
   <int value="1" label="kStatusCodeTypeByClient"/>
   <int value="2" label="kStatusCodeTypeByUser"/>
   <int value="3" label="kStatusCodeTypeConsideredDead"/>
 </enum>
 
+<enum name="WindowsVersion" type="int">
+  <int value="0" label="Pre-XP"/>
+  <int value="1" label="XP"/>
+  <int value="2" label="2003 Server"/>
+  <int value="3" label="Vista"/>
+  <int value="4" label="Windows 7"/>
+  <int value="5" label="Windows 8"/>
+</enum>
+
 </enums>
 
 <!-- Field trials -->
 
 <fieldtrials>
 
 <fieldtrial name="AsyncSlowStart">
   <group name="AsyncSlowStart" label="Async Slow Start on"/>
   <group name="AsyncSlowStart_off" label="Async Slow Start off"/>
   <group name="AsyncSlowStart_on" label="Async Slow Start on"/>
@@ skipping 1097 matching lines @@
 <fieldtrial name="SSLResumption">
   <group name="Resume_Handshake" label="Session Resumption"/>
   <group name="Full_Handshake" label="Full"/>
   <affected-histogram name="Net.SSL_Connection_Latency"/>
   <affected-histogram name="Net.SSL_Connection_Latency_Google"/>
 </fieldtrial>
 
 </fieldtrials>
 
 </histogram-configuration>