Add UMA reporting on failure to load ppapi plugins.

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 56bae39d1dc22d7bd876aed88d1b05e7a0845f9c..8b0234a5500612cdd98dd3be6d4df25b9314ee46 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -2531,6 +2531,14 @@ other types of suffix sets.
   </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.
@@ -4725,6 +4733,13 @@ other types of suffix sets.
   <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"/>
@@ -5236,6 +5251,17 @@ other types of suffix sets.
   <affected-histogram name="Renderer4.BeginToFinishDoc"/>
 </fieldtrial>
 
+<fieldtrial name="PpapiPluginName">

[jar (doing other things), 2013/04/16 18:07:45]

One subtle point: I think you append the group names below with a period.... so
you'll need to add:

<fieldtrial name="PpapiPluginName" separator=".">

You can check to be sure what you have "works" by running
./update_descriptions.py, and looking at the txt file that is generated.

[xhwang, 2013/04/16 19:02:21]

I didn't know about "separator" so I updated my source code to use "_" instead
of ".". (Please see
https://codereview.chromium.org/13548005/diff/77003/content/ppapi_plugin/ppap...)
Is there any recommendation about using "_" or "." as separators?

PS, I don't see update_descriptions.py under src/tools/metrics/histograms. Is it
deprecated?

[jar (doing other things), 2013/04/16 21:12:33]

hmm... I think it must still reside in the internal repo... sorry.  We probably
should have a similar file sitting in that directory... as it can be helpful.

On 2013/04/16 19:02:21, xhwang wrote:

[Ilya Sherman, 2013/04/16 21:58:04]

update_descriptions.py needs to combine data from the public and the internal
repository, so it doesn't really make sense to open-source it.

But, validate_format.py computes all the public histogram description data.  If
you want to see the generated histogram names, you could dump the |histograms|
to a file, or compute |histogram_names =
extract_histograms.ExtractNames(histograms)| first if you just want to see the
names.

+  <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"/>

[jar (doing other things), 2013/04/16 18:07:45]

This is much nicer! thanks!

[xhwang, 2013/04/16 19:02:21]

Thank you for the tip!

+  <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."/>