Add Pepper flag to UMA plugin records.

chrome/common/metrics/proto/system_profile.proto

Index: chrome/common/metrics/proto/system_profile.proto
diff --git a/chrome/common/metrics/proto/system_profile.proto b/chrome/common/metrics/proto/system_profile.proto
index b09dd9811edc5c24734fc37f141a99f4412deef6..65940aba5a3b5bfada4eabfc3c75bb768b7c0f10 100644
--- a/chrome/common/metrics/proto/system_profile.proto
+++ b/chrome/common/metrics/proto/system_profile.proto
@@ -319,6 +319,9 @@ message SystemProfileProto {
     // If a client has multiple local Chrome user accounts, this is logged based
     // on the first user account launched during the current session.
     optional bool is_disabled = 4;
+    
+    // True if the plugin is PPAPI.
+    optional bool is_pepper = 5;
   }
   repeated Plugin plugin = 7;