[Sync] Make chrome sync response compression as default

sync/internal_api/http_bridge.cc

Index: sync/internal_api/http_bridge.cc
diff --git a/sync/internal_api/http_bridge.cc b/sync/internal_api/http_bridge.cc
index 4675e2e1047acf5711a10328cc0a518704eda1ad..59ef7d92711021d7450043b95e90e8bb5a714941 100644
--- a/sync/internal_api/http_bridge.cc
+++ b/sync/internal_api/http_bridge.cc
@@ -47,12 +47,6 @@ 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",
@@ -253,13 +247,6 @@ void HttpBridge::MakeAsynchronousPost() {
   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());