Report PPAPI plugin load error code to UMA.

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 13febe87bdd144ee592cdb25a190e88e32c5e546..85cfcdce573ddc7e7a32f57d1f9021ff83e5010e 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -17701,11 +17701,21 @@ other types of suffix sets.
   <summary>Record usage of PPB_Flash.Navigate() Pepper API.</summary>
 </histogram>
 
+<histogram name="Plugin.PpapiBrokerLoadErrorCode" units="code">
+  <owner>xhwang@chromium.org</owner>
+  <summary>The error code of a PPAPI broker load failure.</summary>
+</histogram>
+
 <histogram name="Plugin.PpapiBrokerLoadResult" enum="PluginLoadResult">
   <owner>xhwang@chromium.org</owner>
   <summary>The result from an attempt to load a PPAPI broker.</summary>
 </histogram>
 
+<histogram name="Plugin.PpapiPluginLoadErrorCode" units="code">
+  <owner>xhwang@chromium.org</owner>
+  <summary>The error code of a PPAPI plugin load failure.</summary>
+</histogram>
+
 <histogram name="Plugin.PpapiPluginLoadResult" enum="PluginLoadResult">
   <owner>xhwang@chromium.org</owner>
   <summary>The result from an attempt to load a PPAPI plugin.</summary>
@@ -41561,7 +41571,9 @@ other types of suffix sets.
   <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.PpapiBrokerLoadErrorCode"/>
   <affected-histogram name="Plugin.PpapiBrokerLoadResult"/>
+  <affected-histogram name="Plugin.PpapiPluginLoadErrorCode"/>
   <affected-histogram name="Plugin.PpapiPluginLoadResult"/>
 </fieldtrial>