[Sync] Make chrome sync response compression as default

sync/internal_api/http_bridge.cc

 // Copyright 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.
 
 #include "sync/internal_api/public/http_bridge.h"
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include <vector>
 
 #include "base/bit_cast.h"
 #include "base/location.h"
 #include "base/message_loop/message_loop.h"
-#include "base/metrics/field_trial.h"
 #include "base/metrics/histogram_macros.h"
 #include "base/metrics/sparse_histogram.h"
 #include "base/single_thread_task_runner.h"
 #include "base/strings/string_number_conversions.h"
-#include "base/strings/string_util.h"
 #include "base/strings/stringprintf.h"
 #include "base/threading/thread_task_runner_handle.h"
 #include "net/base/load_flags.h"
 #include "net/base/net_errors.h"
 #include "net/http/http_cache.h"
 #include "net/http/http_network_layer.h"
 #include "net/http/http_request_headers.h"
 #include "net/http/http_response_headers.h"
 #include "net/url_request/static_http_user_agent_settings.h"
 #include "net/url_request/url_fetcher.h"
 #include "net/url_request/url_request_context.h"
 #include "net/url_request/url_request_job_factory_impl.h"
 #include "net/url_request/url_request_status.h"
 #include "sync/internal_api/public/base/cancelation_signal.h"
 
 namespace syncer {
 
 namespace {
 
 // It's possible for an http request to be silently stalled. We set a time
 // limit for all http requests, beyond which the request is cancelled and
 // treated as a transient failure.
 const int kMaxHttpRequestTimeSeconds = 60 * 5;  // 5 minutes.
 
 // Helper method for logging timeouts via UMA.
 void LogTimeout(bool timed_out) {
   UMA_HISTOGRAM_BOOLEAN("Sync.URLFetchTimedOut", timed_out);
 }
 
-bool IsSyncHttpContentCompressionEnabled() {
-  const std::string group_name =
-      base::FieldTrialList::FindFullName("SyncHttpContentCompression");
-  return StartsWith(group_name, "Enabled", base::CompareCase::SENSITIVE);
-}
-
 void RecordSyncRequestContentLengthHistograms(int64_t compressed_content_length,
                                               int64_t original_content_length) {
   UMA_HISTOGRAM_COUNTS("Sync.RequestContentLength.Compressed",
                        compressed_content_length);
   UMA_HISTOGRAM_COUNTS("Sync.RequestContentLength.Original",
                        original_content_length);
 }
 
 void RecordSyncResponseContentLengthHistograms(
     int64_t compressed_content_length,
@@ skipping 180 matching lines @@
   DCHECK(request_context_getter_.get());
   fetch_state_.start_time = base::Time::Now();
   fetch_state_.url_poster =
       net::URLFetcher::Create(url_for_request_, net::URLFetcher::POST, this)
           .release();
   if (!bind_to_tracker_callback_.is_null())
     bind_to_tracker_callback_.Run(fetch_state_.url_poster);
   fetch_state_.url_poster->SetRequestContext(request_context_getter_.get());
   fetch_state_.url_poster->SetExtraRequestHeaders(extra_headers_);
 
-  if (!IsSyncHttpContentCompressionEnabled()) {
-    // We set "accept-encoding" here to avoid URLRequestHttpJob adding "gzip"
-    // into "accept-encoding" later.
-    fetch_state_.url_poster->AddExtraRequestHeader(base::StringPrintf(
-        "%s: %s", net::HttpRequestHeaders::kAcceptEncoding, "deflate"));
-  }
-
   fetch_state_.url_poster->SetUploadData(content_type_, request_content_);
   RecordSyncRequestContentLengthHistograms(request_content_.size(),
                                            request_content_.size());
 
   fetch_state_.url_poster->AddExtraRequestHeader(base::StringPrintf(
       "%s: %s", net::HttpRequestHeaders::kUserAgent, user_agent_.c_str()));
   fetch_state_.url_poster->SetLoadFlags(net::LOAD_BYPASS_CACHE |
                                         net::LOAD_DISABLE_CACHE |
                                         net::LOAD_DO_NOT_SAVE_COOKIES |
                                         net::LOAD_DO_NOT_SEND_COOKIES);
@@ skipping 186 matching lines @@
   int64_t sane_time_ms = 0;
   if (base::StringToInt64(sane_time_str, &sane_time_ms)) {
     network_time_update_callback_.Run(
         base::Time::FromJsTime(sane_time_ms),
         base::TimeDelta::FromMilliseconds(1),
         fetch_state_.end_time - fetch_state_.start_time);
   }
 }
 
 }  // namespace syncer