Remove unused data reduction proxy prefs from direct settings API.

chrome/common/extensions/api/data_reduction_proxy.json

 // 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.
 
 [
   {
     "namespace": "dataReductionProxy",
     "description": "Use the <code>chrome.dataReductionProxy</code> API to control the data reduction proxy and access usage metrics. This API relies on the <a href='types#ChromeSetting'>ChromeSetting prototype of the type API</a> for getting and setting Chrome's configuration.",
     "properties": {
       "spdyProxyEnabled": {
         "nocompile": true,
         "$ref": "types.ChromeSetting",
         "value": ["spdy_proxy.enabled", {"type":"boolean"}],
         "description": "Flag to enable data usage reduction by sending requests via data reduction proxy. This preference's value is a boolean, defaulting to <code>false</code>."
       },
       "dataReductionDailyContentLength": {
         "nocompile": true,
         "$ref": "types.ChromeSetting",
         "value": ["data_reduction.daily_original_length", {"type":"array"}],
         "description": "Each item contains the number uncompressed bytes through data reduction proxy per day."
       },
       "dataReductionDailyReceivedLength": {
         "nocompile": true,
         "$ref": "types.ChromeSetting",
         "value": ["data_reduction.daily_received_length", {"type":"array"}],
         "description": "Each item contains the number of compressed bytes through data reduction proxy per day."
-      },
-      "dataReductionUpdateDailyLengths": {
-        "nocompile": true,
-        "$ref": "types.ChromeSetting",
-        "value": ["data_reduction.update_daily_lengths", {"type":"boolean"}],
-        "description": "Flag to indicate that dataReductionDailyContentLength and dataReductionDailyReceivedLength must be updated with their latest values. This preference's value is a boolean, defaulting to <code>false</code>."
       }
     },
     "functions": [
       {
         "name": "clearDataSavings",
         "type": "function",
         "description": "Clear all data saving metrics obtained by using the data reduction proxy.",
         "parameters": [
           {
             "type": "function",
             "name": "callback",
             "description": "Callback to call after data savings have been cleared",
             "optional": true,
             "parameters": []
           }
         ]
       }
     ]
   }
 ]