Add UMA reporting on failure to load ppapi plugins.

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 2582 matching lines @@
 </histogram>
 
 <histogram name="PLT.StartToFinish" units="milliseconds">
   <summary>
     Time from &quot;start&quot; to &quot;finish.&quot; &quot;Start&quot;== time
     when renderer requested load of document, after any unload of last document.
     &quot;Finish&quot;==after onload() and all resources are loaded.
   </summary>
 </histogram>
 
+<histogram name="Plugin.PpapiBrokerLoadResult" enum="PluginLoadResult">
+  <summary>The result from an attempt to load a PPAPI broker.</summary>
+</histogram>
+
+<histogram name="Plugin.PpapiPluginLoadResult" enum="PluginLoadResult">
+  <summary>The result from an attempt to load a PPAPI plugin.</summary>
+</histogram>
+
 <histogram name="Prerender.FinalStatus" enum="PrerenderFinalStatus">
   <summary>
     Final status for prerender pages - either success, or why it was canceled.
   </summary>
 </histogram>
 
 <histogram name="Prerender.FinalStatusMatchComplete"
     enum="PrerenderFinalStatus">
   <summary>
     Final status for prerender pages - either success, or why it was canceled.
@@ skipping 2266 matching lines @@
   <int value="8" label="NO_SPACE"/>
   <int value="9" label="NOT_A_DIRECTORY"/>
   <int value="10" label="INVALID_OPERATION"/>
   <int value="11" label="SECURITY"/>
   <int value="12" label="ABORT"/>
   <int value="13" label="NOT_A_FILE"/>
   <int value="14" label="NOT_EMPTY"/>
   <int value="15" label="INVALID_URL"/>
 </enum>
 
+<enum name="PluginLoadResult" type="int">
+  <int value="0" label="LOAD_SUCCESS"/>
+  <int value="1" label="LOAD_FAILED"/>
+  <int value="2" label="ENTRY_POINT_MISSING"/>
+  <int value="3" label="INIT_FAILED"/>
+</enum>
+
 <enum name="PreconnectMotivation" type="int">
   <int value="0" label="MOUSE_OVER_MOTIVATED"/>
   <int value="1" label="PAGE_SCAN_MOTIVATED"/>
   <int value="2" label="UNIT_TEST_MOTIVATED"/>
   <int value="3" label="LINKED_MAX_MOTIVATED"/>
   <int value="4" label="OMNIBOX_MOTIVATED"/>
   <int value="5" label="STARTUP_LIST_MOTIVATED"/>
   <int value="6" label="EARLY_LOAD_MOTIVATED"/>
   <int value="7" label="NO_PREFETCH_MOTIVATION"/>
   <int value="8" label="STATIC_REFERAL_MOTIVATED"/>
@@ skipping 491 matching lines @@
     <with-group name="NormalLoad"/>
   </affected-histogram>
   <affected-histogram name="PLT.StartToFinish">
     <with-group name="LinkLoadNormal"/>
     <with-group name="NormalLoad"/>
   </affected-histogram>
   <affected-histogram name="Renderer4.BeginToFinish"/>
   <affected-histogram name="Renderer4.BeginToFinishDoc"/>
 </fieldtrial>
 
+<fieldtrial name="PpapiPluginName">
+  <group name="libpepflashplayer.so" label="Flash player on Linux or Cros"/>
+  <group name="libwidevinecdmadapter.so" label="Widevine CDM on Linux or Cros"/>
+  <group name="pepflashplayer.dll" label="Flash player on Windows"/>
+  <group name="PepperFlashPlayer.plugin" label="Flash player on Mac"/>
+  <group name="widevinecdmadapter.dll" label="Widevine CDM on Windows"/>
+  <group name="widevinecdmadapter.plugin" label="Widevine CDM on Mac"/>
+  <affected-histogram name="Plugin.PpapiBrokerLoadResult"/>
+  <affected-histogram name="Plugin.PpapiPluginLoadResult"/>
+</fieldtrial>
+
 <fieldtrial name="Prefetch">
   <group name="ContentPrefetchPrefetchOff"
       label="Prefetch is completely disabled."/>
   <group name="ContentPrefetchPrefetchOn"
       label="prefetch is enabled but prerender is disabled."/>
   <affected-histogram name="HttpCache.EntryLockWait"/>
   <affected-histogram name="Net.HttpTimeToFirstByte"/>
   <affected-histogram name="PLT.Abandoned"/>
   <affected-histogram name="PLT.BeginToFinish"/>
   <affected-histogram name="PLT.BeginToFinish_ContentPrefetcher"/>
@@ skipping 140 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>