Support moving pending requests from one DataUseRecorder to another

components/data_use_measurement/core/data_use_recorder.cc

 // 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.
 
 #include "components/data_use_measurement/core/data_use_recorder.h"
 
 #include "net/url_request/url_request.h"
 
 namespace data_use_measurement {
 
 DataUseRecorder::DataUseRecorder(DataUse::TrafficType traffic_type)
     : main_url_request_(nullptr), data_use_(traffic_type), is_visible_(false) {}
 
 DataUseRecorder::~DataUseRecorder() {}
 
 bool DataUseRecorder::IsDataUseComplete() {
-  return pending_url_requests_.empty() && pending_data_sources_.empty();
+  return pending_url_requests_.empty();
 }
 
 void DataUseRecorder::AddPendingURLRequest(net::URLRequest* request) {
-  pending_url_requests_.insert(request);
+  pending_url_requests_.emplace(std::piecewise_construct,
+                                std::forward_as_tuple(request),
+                                std::forward_as_tuple());
 }
 
 void DataUseRecorder::OnUrlRequestDestroyed(net::URLRequest* request) {
   pending_url_requests_.erase(request);
 }
 
+void DataUseRecorder::MovePendingURLRequest(DataUseRecorder* other,
+                                            net::URLRequest* request) {
+  auto request_it = pending_url_requests_.find(request);
+  DCHECK(request_it != pending_url_requests_.end());
+  DCHECK(other->pending_url_requests_.find(request) ==
+         other->pending_url_requests_.end());
+
+  // Move the bytes of the request from |this| to |other|.
+  // TODO(rajendrant): Check if the moving the bytes in |data_use_| needs to be
+  // propogated to observers, which could store per-request user data.
+  other->AddPendingURLRequest(request);
+  other->UpdateNetworkByteCounts(request, request_it->second.bytes_received,
+                                 request_it->second.bytes_sent);
+  data_use_.IncrementTotalBytes(-request_it->second.bytes_received,

[tbansal1, 2017/06/26 21:44:28]

nit: Add a comment on why this is negative.

[Raj, 2017/06/27 02:30:04]

Done

+                                -request_it->second.bytes_sent);
+  pending_url_requests_.erase(request_it);
+}
+
 void DataUseRecorder::RemoveAllPendingURLRequests() {
   pending_url_requests_.clear();
 }
 
 void DataUseRecorder::OnBeforeUrlRequest(net::URLRequest* request) {}
 
 void DataUseRecorder::OnNetworkBytesReceived(net::URLRequest* request,
                                              int64_t bytes_received) {
-  data_use_.IncrementTotalBytes(bytes_received, 0);
+  UpdateNetworkByteCounts(request, bytes_received, 0);
 }
 
 void DataUseRecorder::OnNetworkBytesSent(net::URLRequest* request,
                                          int64_t bytes_sent) {
-  data_use_.IncrementTotalBytes(0, bytes_sent);
+  UpdateNetworkByteCounts(request, 0, bytes_sent);
 }
 
-void DataUseRecorder::MergeFrom(DataUseRecorder* other) {
-  data_use_.MergeFrom(other->data_use());
+void DataUseRecorder::UpdateNetworkByteCounts(net::URLRequest* request,
+                                              int64_t bytes_received,
+                                              int64_t bytes_sent) {
+  data_use_.IncrementTotalBytes(bytes_received, bytes_sent);
+  auto request_it = pending_url_requests_.find(request);
+  request_it->second.bytes_received += bytes_received;
+  request_it->second.bytes_sent += bytes_sent;
 }
 
 }  // namespace data_use_measurement