Block NPAPI plugins by default

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 3b988f4116b51926eba813aa1b199ed752a698f5..cd457df6c9b7cb07156e45e0a884347482db598a 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -25874,6 +25874,14 @@ Therefore, the affected-histogram name has to have at least one dot in it.
   <summary>Collects Flash usage data.</summary>
 </histogram>
 
+<histogram name="Plugin.NPAPIStatus" enum="NPAPIPluginStatus">
+  <owner>wfh@chromium.org</owner>
+  <summary>
+    Records whether NPAPI plugins are supported by the platform, and if so,
+    whether they are enabled or disabled.  Recorded once at browser startup.
+  </summary>
+</histogram>
+
 <histogram name="Plugin.PowerSaver.PeripheralHeuristic"
     enum="PluginPowerSaverPeripheralHeuristicDecision">
   <owner>tommycli@chromium.org</owner>
@@ -50269,6 +50277,7 @@ To add a new entry, add it with any value and run test to compute valid value.
   <int value="-1218608640" label="disable-offline-load-stale-cache"/>
   <int value="-1212273428" label="enable-experimental-app-list"/>
   <int value="-1201183153" label="enable-centered-app-list"/>
+  <int value="-1184904651" label="enable-npapi"/>
   <int value="-1177802205" label="enable-hosted-app-quit-notification"/>
   <int value="-1172204005" label="enable-offline-auto-reload-visible-only"/>
   <int value="-1159563774" label="enable-accessibility-script-injection"/>
@@ -52390,6 +52399,14 @@ To add a new entry, add it with any value and run test to compute valid value.
   <int value="7" label="Notification closed by system"/>
 </enum>
 
+<enum name="NPAPIPluginStatus" type="int">
+  <int value="0" label="Unsupported">
+    NPAPI is not supported on this platform
+  </int>
+  <int value="1" label="Disabled">NPAPI is disabled</int>
+  <int value="2" label="Enabled">NPAPI is enabled</int>
+</enum>
+
 <enum name="NtpFollowAction" type="int">
   <int value="0" label="PAGE_TRANSITION_LINK"/>
   <int value="1" label="PAGE_TRANSITION_TYPED"/>