predictors: Add origin learning.

chrome/browser/predictors/resource_prefetch_predictor.proto

 // Copyright 2016 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.
 
 // Protocol buffers used for storing in SQLite.
 // CAUTION: When any change is done here, bump kDatabaseVersion in
 //          resource_prefetch_predictor_tables.h.
 
 syntax = "proto2";
 
@@ skipping 65 matching lines @@
     optional uint32 number_of_hits = 2;
     optional uint32 number_of_misses = 3;
     optional uint32 consecutive_misses = 4;
   }
 
   // Main frame URL or host.
   optional string primary_key = 1;
   optional uint64 last_visit_time = 2;
   repeated RedirectStat redirect_endpoints = 3;
 }
+
+// Historical data for a single origin accessed from a host.
+message OriginStat {
+  optional string origin = 1;
+  optional uint32 number_of_hits = 2;
+  optional uint32 number_of_misses = 3;
+  optional uint32 consecutive_misses = 4;
+  optional double average_position = 5;
+  optional bool always_access_network = 6;
+  optional bool accessed_network = 7;
+}
+
+// Collection of origins accessed from a host.
+message OriginData {
+  optional string host = 1;
+  optional uint64 last_visit_time = 2;
+  repeated OriginStat origins = 3;
+}