chrome/browser/sessions/tab_loader_delegate.cc

   1 // Copyright 2014 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "chrome/browser/sessions/tab_loader_delegate.h"
   6
   7 #include "net/base/network_change_notifier.h"
   8
   9 namespace {
  10
  11 // The timeout time after which the next tab gets loaded if the previous tab did
  12 // not finish loading yet. The used value is half of the median value of all
  13 // ChromeOS devices loading the 25 most common web pages. Half is chosen since
  14 // the loading time is a mix of server response and data bandwidth.
  15 static const int kInitialDelayTimerMS = 1500;
  16
  17 class TabLoaderDelegateImpl
  18     : public TabLoaderDelegate,
  19       public net::NetworkChangeNotifier::ConnectionTypeObserver {
  20  public:
  21   explicit TabLoaderDelegateImpl(TabLoaderCallback* callback);
  22   ~TabLoaderDelegateImpl() override;
  23
  24   // TabLoaderDelegate:
  25   base::TimeDelta GetTimeoutBeforeLoadingNextTab() const override {
  26     return base::TimeDelta::FromMilliseconds(kInitialDelayTimerMS);
  27   }
  28
  29   // net::NetworkChangeNotifier::ConnectionTypeObserver:
  30   void OnConnectionTypeChanged(
  31       net::NetworkChangeNotifier::ConnectionType type) override;
  32
  33  private:
  34   // The function to call when the connection type changes.
  35   TabLoaderCallback* callback_;
  36
  37   DISALLOW_COPY_AND_ASSIGN(TabLoaderDelegateImpl);
  38 };
  39
  40 TabLoaderDelegateImpl::TabLoaderDelegateImpl(TabLoaderCallback* callback)
  41     : callback_(callback) {
  42   net::NetworkChangeNotifier::AddConnectionTypeObserver(this);
  43   if (net::NetworkChangeNotifier::IsOffline()) {
  44     // When we are off-line we do not allow loading of tabs, since each of
  45     // these tabs would start loading simultaneously when going online.
  46     // TODO(skuhne): Once we get a higher level resource control logic which
  47     // distributes network access, we can remove this.
  48     callback->SetTabLoadingEnabled(false);
  49   }
  50 }
  51
  52 TabLoaderDelegateImpl::~TabLoaderDelegateImpl() {
  53   net::NetworkChangeNotifier::RemoveConnectionTypeObserver(this);
  54 }
  55
  56 void TabLoaderDelegateImpl::OnConnectionTypeChanged(
  57     net::NetworkChangeNotifier::ConnectionType type) {
  58   callback_->SetTabLoadingEnabled(
  59       type != net::NetworkChangeNotifier::CONNECTION_NONE);
  60 }
  61 }  // namespace
  62
  63 // static
  64 scoped_ptr<TabLoaderDelegate> TabLoaderDelegate::Create(
  65     TabLoaderCallback* callback) {
  66   return scoped_ptr<TabLoaderDelegate>(
  67       new TabLoaderDelegateImpl(callback));
  68 }