Handle malformed built-in PluginFinder data.

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 ab123224f2860a2b8f78e77c1057028c1e7c0773..9877b2cbd6394af45ebb47e2f9d0b4fc24bf3cd8 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -28658,6 +28658,15 @@ Therefore, the affected-histogram name has to have at least one dot in it.
   </summary>
 </histogram>
 
+<histogram name="PluginFinder.BuiltInPluginList.ErrorCode"
+    enum="PluginListError">
+  <owner>bauerb@chromium.org</owner>
+  <summary>
+    Error codes when parsing the built-in plugin list. Logged when the
+    PluginFinder singleton is created.
+  </summary>
+</histogram>
+
 <histogram name="Power.BacklightLevelOnAC" units="%">
   <owner>derat@chromium.org</owner>
   <summary>
@@ -58978,6 +58987,19 @@ To add a new entry, add it with any value and run test to compute valid value.
   <int value="2" label="PLUGIN_DISABLED"/>
 </enum>
 
+<enum name="PluginListError" type="int">
+  <int value="0" label="NoError"/>
+  <int value="1" label="JsonInvalidEscape"/>
+  <int value="2" label="JsonSyntaxError"/>
+  <int value="3" label="JsonUnexpectedToken"/>
+  <int value="4" label="JsonTrailingComma"/>
+  <int value="5" label="JsonTooMuchNesting"/>
+  <int value="6" label="JsonUnexpectedDataAfterRoot"/>
+  <int value="7" label="JsonUnsupportedEncoding"/>
+  <int value="8" label="JsonUnquotedDictionaryKey"/>
+  <int value="9" label="SchemaError"/>
+</enum>
+
 <enum name="PluginLoadResult" type="int">
   <int value="0" label="LOAD_SUCCESS"/>
   <int value="1" label="LOAD_FAILED"/>