Add sampling of unknown filetypes in download protection.

chrome/common/safe_browsing/csd.proto

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 //
 // This proto file includes:
 // (1) Client side phishing and malware detection request and response
 //   protocol buffers.  Those protocol messages should be kept in sync
 //   with the server implementation.
 //
 // (2) Safe Browsing reporting protocol buffers.
@@ skipping 268 matching lines @@
     // .zip files containing one of the other executable types.
     ZIPPED_EXECUTABLE = 3;
     MAC_EXECUTABLE = 4;  // .dmg, .pkg, etc.
     ZIPPED_ARCHIVE = 5;  // .zip file containing another archive.
     ARCHIVE = 6;         // Archive that doesn't have a specific DownloadType.
     // A .zip that Chrome failed to unpack to the point of finding exe/zips.
     INVALID_ZIP = 7;
     // A .dmg, .pkg, etc, that Chrome failed to unpack to the point of finding
     // Mach O's.
     INVALID_MAC_ARCHIVE = 8;
-    PPAPI_SAVE_REQUEST =
-        9;  // A download request initiated via PPAPI. Typically
-            // the requestor is a Flash applet.
+    // A download request initiated via PPAPI. Typically the requestor is
+    // a Flash applet.
+    PPAPI_SAVE_REQUEST = 9;
+    // A file we don't support, but we've decided to sample and send
+    // a light-ping.
+    SAMPLED_UNSUPPORTED_FILE = 10;
   }
   optional DownloadType download_type = 10 [default = WIN_EXECUTABLE];
 
   // Locale of the device, eg en, en_US.
   optional string locale = 11;
 
   message PEImageHeaders {
     // IMAGE_DOS_HEADER.
     optional bytes dos_header = 1;
     // IMAGE_FILE_HEADER.
@@ skipping 483 matching lines @@
   optional bool did_proceed = 8;
 
   // Whether user visited this origin before.
   optional bool repeat_visit = 9;
 
   // The same token in ClientDownloadResponse. This field is only set if its
   // report type is DANGEROUS_DOWNLOAD_RECOVERY, DANGEROUS_DOWNLOAD_WARNING or
   // DANGEROUS_DOWNLOAD_BY_API.
   optional bytes token = 15;
 }