Roll dom_distiller_js and add UMA for word count for distilled pages.

third_party/dom_distiller_js/package/proto/dom_distiller.proto

 // Copyright 2014 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.
 
 syntax = "proto2";
 
 package dom_distiller.proto;
 option optimize_for = LITE_RUNTIME;
 option java_package = "com.dom_distiller.proto";
 option java_outer_classname = "DomDistillerProtos";
@@ skipping 42 matching lines @@
   optional double document_construction_time = 2;
   optional double article_processing_time = 3;
   optional double formatting_time = 4;
   optional double total_time = 5;
 }
 
 message DebugInfo {
   optional string log = 1;
 }
 
+message StatisticsInfo {
+  optional int32 word_count = 1;
+}
+
 message DomDistillerResult {
   optional string title = 1;
   optional DistilledContent distilled_content = 2;
   optional PaginationInfo pagination_info = 3;
   repeated string image_urls = 4;
   optional MarkupInfo markup_info = 5;
   optional TimingInfo timing_info = 6;
   optional DebugInfo debug_info = 7;
+  optional StatisticsInfo statistics_info = 8;
 }
 
 message DomDistillerOptions {
   // Whether to extract only the text (or to include the containing html).
   optional bool extract_text_only = 1;
 
   // How much debug output to dump to window.console.
   // (0): Logs nothing
   // (1): Text Node data for each stage of processing
   // (2): (1) and some node visibility information
   // (3): (2) and extracted paging information
   optional int32 debug_level = 2;
 }