Revert 99666 (sync tests started failing on mac10.6:

http://build.chromium.org/p/chromium/builders/Mac10.6%20Sync/builds/9198

- Linux: Monitor resolv.conf for changes and use that to reload resolver.

BUG=67734
TEST=manual testing by poking at resolv.conf

Review URL: http://codereview.chromium.org/6903061

TBR=craig.schlenter@chromium.org
Review URL: http://codereview.chromium.org/7833030

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@99677 0039d316-1c4b-4281-b951-d872f2087c98

12 files changed, 187 insertions, 319 deletions

diff --git a/net/base/dns_reload_timer.cc b/net/base/dns_reload_timer.cc
new file mode 100644
index 0000000..89bda59
--- /dev/null
+++ b/net/base/dns_reload_timer.cc
@@ -0,0 +1,100 @@
+// Copyright (c) 2010 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 "net/base/dns_reload_timer.h"
+
+#if defined(OS_POSIX) && !defined(OS_MACOSX) && !defined(OS_OPENBSD)
+#include "base/lazy_instance.h"
+#include "base/threading/thread_local_storage.h"
+#include "base/time.h"
+
+namespace {
+
+// On Linux/BSD, changes to /etc/resolv.conf can go unnoticed thus resulting
+// in DNS queries failing either because nameservers are unknown on startup
+// or because nameserver info has changed as a result of e.g. connecting to
+// a new network. Some distributions patch glibc to stat /etc/resolv.conf
+// to try to automatically detect such changes but these patches are not
+// universal and even patched systems such as Jaunty appear to need calls
+// to res_ninit to reload the nameserver information in different threads.
+//
+// We adopt the Mozilla solution here which is to call res_ninit when
+// lookups fail and to rate limit the reloading to once per second per
+// thread.
+//
+// OpenBSD does not have thread-safe res_ninit/res_nclose so we can't do
+// the same trick there.
+
+// Keep a timer per calling thread to rate limit the calling of res_ninit.
+class DnsReloadTimer {
+ public:
+  // Check if the timer for the calling thread has expired. When no
+  // timer exists for the calling thread, create one.
+  bool Expired() {
+    const base::TimeDelta kRetryTime = base::TimeDelta::FromSeconds(1);
+    base::TimeTicks now = base::TimeTicks::Now();
+    base::TimeTicks* timer_ptr =
+      static_cast<base::TimeTicks*>(tls_index_.Get());
+
+    if (!timer_ptr) {
+      timer_ptr = new base::TimeTicks();
+      *timer_ptr = base::TimeTicks::Now();
+      tls_index_.Set(timer_ptr);
+      // Return true to reload dns info on the first call for each thread.
+      return true;
+    } else if (now - *timer_ptr > kRetryTime) {
+      *timer_ptr = now;
+      return true;
+    } else {
+      return false;
+    }
+  }
+
+  // Free the allocated timer.
+  static void SlotReturnFunction(void* data) {
+    base::TimeTicks* tls_data = static_cast<base::TimeTicks*>(data);
+    delete tls_data;
+  }
+
+ private:
+  friend struct base::DefaultLazyInstanceTraits<DnsReloadTimer>;
+
+  DnsReloadTimer() {
+    // During testing the DnsReloadTimer Singleton may be created and destroyed
+    // multiple times. Initialize the ThreadLocalStorage slot only once.
+    if (!tls_index_.initialized())
+      tls_index_.Initialize(SlotReturnFunction);
+  }
+
+  ~DnsReloadTimer() {
+  }
+
+  // We use thread local storage to identify which base::TimeTicks to
+  // interact with.
+  static base::ThreadLocalStorage::Slot tls_index_ ;
+
+  DISALLOW_COPY_AND_ASSIGN(DnsReloadTimer);
+};
+
+// A TLS slot to the TimeTicks for the current thread.
+// static
+base::ThreadLocalStorage::Slot DnsReloadTimer::tls_index_(
+    base::LINKER_INITIALIZED);
+
+base::LazyInstance<DnsReloadTimer,
+                   base::LeakyLazyInstanceTraits<DnsReloadTimer> >
+    g_dns_reload_timer(base::LINKER_INITIALIZED);
+
+}  // namespace
+
+namespace net {
+
+bool DnsReloadTimerHasExpired() {
+  DnsReloadTimer* dns_timer = g_dns_reload_timer.Pointer();
+  return dns_timer->Expired();
+}
+
+}  // namespace net
+
+#endif  // defined(OS_POSIX) && !defined(OS_MACOSX) && !defined(OS_OPENBSD)
diff --git a/net/base/dns_reload_timer.h b/net/base/dns_reload_timer.h
new file mode 100644
index 0000000..fdd90a7
--- /dev/null
+++ b/net/base/dns_reload_timer.h
@@ -0,0 +1,22 @@
+// Copyright (c) 2009 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.
+
+#ifndef NET_BASE_DNS_RELOAD_TIMER_H_
+#define NET_BASE_DNS_RELOAD_TIMER_H_
+#pragma once
+
+#include "build/build_config.h"
+
+#if defined(OS_POSIX) && !defined(OS_MACOSX) && !defined(OS_OPENBSD)
+namespace net {
+
+// DnsReloadTimerExpired tests the thread local DNS reload timer and, if it has
+// expired, returns true and resets the timer. See comments in
+// host_resolver_proc.cc for details.
+bool DnsReloadTimerHasExpired();
+
+}  // namespace net
+#endif
+
+#endif  // NET_BASE_DNS_RELOAD_TIMER_H_
diff --git a/net/base/dns_reloader.cc b/net/base/dns_reloader.cc
deleted file mode 100644
index d45c145..0000000
--- a/net/base/dns_reloader.cc
+++ /dev/null
@@ -1,122 +0,0 @@
-// Copyright (c) 2011 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 "net/base/dns_reloader.h"
-
-#if defined(OS_POSIX) && !defined(OS_MACOSX) && !defined(OS_OPENBSD)
-
-#include <resolv.h>
-
-#include "base/basictypes.h"
-#include "base/lazy_instance.h"
-#include "base/logging.h"
-#include "base/message_loop.h"
-#include "base/synchronization/lock.h"
-#include "base/threading/thread_local_storage.h"
-#include "net/base/network_change_notifier.h"
-
-namespace {
-
-// On Linux/BSD, changes to /etc/resolv.conf can go unnoticed thus resulting
-// in DNS queries failing either because nameservers are unknown on startup
-// or because nameserver info has changed as a result of e.g. connecting to
-// a new network. Some distributions patch glibc to stat /etc/resolv.conf
-// to try to automatically detect such changes but these patches are not
-// universal and even patched systems such as Jaunty appear to need calls
-// to res_ninit to reload the nameserver information in different threads.
-//
-// To fix this, on systems with FilePathWatcher support, we use
-// NetworkChangeNotifier::DNSObserver to monitor /etc/resolv.conf to
-// enable us to respond to DNS changes and reload the resolver state.
-//
-// OpenBSD does not have thread-safe res_ninit/res_nclose so we can't do
-// the same trick there and most *BSD's don't yet have support for
-// FilePathWatcher (but perhaps the new kqueue mac code just needs to be
-// ported to *BSD to support that).
-
-class DnsReloader : public net::NetworkChangeNotifier::DNSObserver {
- public:
-  struct ReloadState {
-    int resolver_generation;
-  };
-
-  // NetworkChangeNotifier::OnDNSChanged methods:
-  virtual void OnDNSChanged() OVERRIDE {
-    DCHECK_EQ(MessageLoop::current()->type(), MessageLoop::TYPE_IO);
-    base::AutoLock l(lock_);
-    resolver_generation_++;
-  }
-
-  void MaybeReload() {
-    ReloadState* reload_state = static_cast<ReloadState*>(tls_index_.Get());
-    base::AutoLock l(lock_);
-
-    if (!reload_state) {
-      reload_state = new ReloadState();
-      reload_state->resolver_generation = resolver_generation_;
-      res_ninit(&_res);
-      tls_index_.Set(reload_state);
-    } else if (reload_state->resolver_generation != resolver_generation_) {
-      reload_state->resolver_generation = resolver_generation_;
-      // It is safe to call res_nclose here since we know res_ninit will have
-      // been called above.
-      res_nclose(&_res);
-      res_ninit(&_res);
-    }
-  }
-
-  // Free the allocated state.
-  static void SlotReturnFunction(void* data) {
-    ReloadState* reload_state = static_cast<ReloadState*>(data);
-    if (reload_state)
-      res_nclose(&_res);
-    delete reload_state;
-  }
-
- private:
-  DnsReloader() : resolver_generation_(0) {
-    tls_index_.Initialize(SlotReturnFunction);
-    net::NetworkChangeNotifier::AddDNSObserver(this);
-  }
-
-  ~DnsReloader() {
-    NOTREACHED();  // LeakyLazyInstance is not destructed.
-  }
-
-  base::Lock lock_;  // Protects resolver_generation_.
-  int resolver_generation_;
-  friend struct base::DefaultLazyInstanceTraits<DnsReloader>;
-
-  // We use thread local storage to identify which ReloadState to interact with.
-  static base::ThreadLocalStorage::Slot tls_index_ ;
-
-  DISALLOW_COPY_AND_ASSIGN(DnsReloader);
-};
-
-// A TLS slot to the ReloadState for the current thread.
-// static
-base::ThreadLocalStorage::Slot DnsReloader::tls_index_(
-    base::LINKER_INITIALIZED);
-
-base::LazyInstance<DnsReloader,
-                   base::LeakyLazyInstanceTraits<DnsReloader> >
-    g_dns_reloader(base::LINKER_INITIALIZED);
-
-}  // namespace
-
-namespace net {
-
-void EnsureDnsReloaderInit() {
-  DnsReloader* t ALLOW_UNUSED = g_dns_reloader.Pointer();
-}
-
-void DnsReloaderMaybeReload() {
-  // This routine can be called by any of the DNS worker threads.
-  DnsReloader* dns_reloader = g_dns_reloader.Pointer();
-  dns_reloader->MaybeReload();
-}
-
-}  // namespace net
-
-#endif  // defined(OS_POSIX) && !defined(OS_MACOSX) && !defined(OS_OPENBSD)
diff --git a/net/base/dns_reloader.h b/net/base/dns_reloader.h
deleted file mode 100644
index 899fbf3..0000000
--- a/net/base/dns_reloader.h
+++ /dev/null
@@ -1,24 +0,0 @@
-// Copyright (c) 2011 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.
-
-#ifndef NET_BASE_DNS_RELOADER_H_
-#define NET_BASE_DNS_RELOADER_H_
-#pragma once
-
-#include "build/build_config.h"
-
-#if defined(OS_POSIX) && !defined(OS_MACOSX) && !defined(OS_OPENBSD)
-namespace net {
-
-// Call on the network thread before calling DnsReloaderMaybeReload() anywhere.
-void EnsureDnsReloaderInit();
-
-// Call on the worker thread before doing a DNS lookup to reload the
-// resolver for that thread by doing res_ninit() if required.
-void DnsReloaderMaybeReload();
-
-}  // namespace net
-#endif  // defined(OS_POSIX) && !defined(OS_MACOSX) && !defined(OS_OPENBSD)
-
-#endif  // NET_BASE_DNS_RELOADER_H_
diff --git a/net/base/dnsrr_resolver.cc b/net/base/dnsrr_resolver.cc
index e0d43d9..2cfb0cf 100644
--- a/net/base/dnsrr_resolver.cc
+++ b/net/base/dnsrr_resolver.cc
@@ -20,7 +20,7 @@
 #include "base/synchronization/lock.h"
 #include "base/task.h"
 #include "base/threading/worker_pool.h"
-#include "net/base/dns_reloader.h"
+#include "net/base/dns_reload_timer.h"
 #include "net/base/dns_util.h"
 #include "net/base/net_errors.h"
 
@@ -184,18 +184,26 @@ class RRResolverWorker {
     }
 
     bool r = true;
-#if defined(OS_MACOSX) || defined(OS_OPENBSD)
     if ((_res.options & RES_INIT) == 0) {
       if (res_ninit(&_res) != 0)
         r = false;
     }
-#else
-    DnsReloaderMaybeReload();
-#endif
 
     if (r) {
       unsigned long saved_options = _res.options;
       r = Do();
+
+#if defined(OS_POSIX) && !defined(OS_MACOSX) && !defined(OS_OPENBSD)
+      if (!r && DnsReloadTimerHasExpired()) {
+        // When there's no network connection, _res may not be initialized by
+        // getaddrinfo. Therefore, we call res_nclose only when there are ns
+        // entries.
+        if (_res.nscount > 0)
+          res_nclose(&_res);
+        if (res_ninit(&_res) == 0)
+          r = Do();
+      }
+#endif
       _res.options = saved_options;
     }
 
diff --git a/net/base/host_resolver_impl.cc b/net/base/host_resolver_impl.cc
index 7d6e3e2..840d263 100644
--- a/net/base/host_resolver_impl.cc
+++ b/net/base/host_resolver_impl.cc
@@ -30,7 +30,6 @@
 #include "base/values.h"
 #include "net/base/address_list.h"
 #include "net/base/address_list_net_log_param.h"
-#include "net/base/dns_reloader.h"
 #include "net/base/host_port_pair.h"
 #include "net/base/host_resolver_proc.h"
 #include "net/base/net_errors.h"
@@ -1091,10 +1090,6 @@ HostResolverImpl::HostResolverImpl(
     additional_resolver_flags_ |= HOST_RESOLVER_LOOPBACK_ONLY;
 #endif
   NetworkChangeNotifier::AddIPAddressObserver(this);
-#if defined(OS_POSIX) && !defined(OS_MACOSX) && !defined(OS_OPENBSD)
-  EnsureDnsReloaderInit();
-  NetworkChangeNotifier::AddDNSObserver(this);
-#endif
 }
 
 HostResolverImpl::~HostResolverImpl() {
@@ -1109,9 +1104,6 @@ HostResolverImpl::~HostResolverImpl() {
     cur_completing_job_->Cancel();
 
   NetworkChangeNotifier::RemoveIPAddressObserver(this);
-#if defined(OS_POSIX) && !defined(OS_MACOSX) && !defined(OS_OPENBSD)
-  NetworkChangeNotifier::RemoveDNSObserver(this);
-#endif
 
   // Delete the job pools.
   for (size_t i = 0u; i < arraysize(job_pools_); ++i)
@@ -1652,17 +1644,4 @@ void HostResolverImpl::OnIPAddressChanged() {
   // |this| may be deleted inside AbortAllInProgressJobs().
 }
 
-void HostResolverImpl::OnDNSChanged() {
-  // If the DNS server has changed, existing cached info could be wrong so we
-  // have to drop our internal cache :( Note that OS level DNS caches, such
-  // as NSCD's cache should be dropped automatically by the OS when
-  // resolv.conf changes so we don't need to do anything to clear that cache.
-  if (cache_.get())
-    cache_->clear();
-  // Existing jobs will have been sent to the original server so they need to
-  // be aborted. TODO(Craig): Should these jobs be restarted?
-  AbortAllInProgressJobs();
-  // |this| may be deleted inside AbortAllInProgressJobs().
-}
-
 }  // namespace net
diff --git a/net/base/host_resolver_impl.h b/net/base/host_resolver_impl.h
index 4c4581e..30772df 100644
--- a/net/base/host_resolver_impl.h
+++ b/net/base/host_resolver_impl.h
@@ -62,8 +62,7 @@ namespace net {
 class NET_EXPORT HostResolverImpl
     : public HostResolver,
       NON_EXPORTED_BASE(public base::NonThreadSafe),
-      public NetworkChangeNotifier::IPAddressObserver,
-      public NetworkChangeNotifier::DNSObserver {
+      public NetworkChangeNotifier::IPAddressObserver {
  public:
   // The index into |job_pools_| for the various job pools. Pools with a higher
   // index have lower priority.
@@ -305,9 +304,6 @@ class NET_EXPORT HostResolverImpl
     retry_factor_ = retry_factor;
   }
 
-  // NetworkChangeNotifier::OnDNSChanged methods:
-  virtual void OnDNSChanged();
-
   // Cache of host resolution results.
   scoped_ptr<HostCache> cache_;
 
diff --git a/net/base/host_resolver_proc.cc b/net/base/host_resolver_proc.cc
index 331675a..755f119 100644
--- a/net/base/host_resolver_proc.cc
+++ b/net/base/host_resolver_proc.cc
@@ -8,7 +8,7 @@
 
 #include "base/logging.h"
 #include "net/base/address_list.h"
-#include "net/base/dns_reloader.h"
+#include "net/base/dns_reload_timer.h"
 #include "net/base/net_errors.h"
 #include "net/base/sys_addrinfo.h"
 
@@ -183,12 +183,22 @@ int SystemHostResolverProc(const std::string& host,
   // Restrict result set to only this socket type to avoid duplicates.
   hints.ai_socktype = SOCK_STREAM;
 
+  int err = getaddrinfo(host.c_str(), NULL, &hints, &ai);
+  bool should_retry = false;
 #if defined(OS_POSIX) && !defined(OS_MACOSX) && !defined(OS_OPENBSD) && \
     !defined(OS_ANDROID)
-  DnsReloaderMaybeReload();
+  // If we fail, re-initialise the resolver just in case there have been any
+  // changes to /etc/resolv.conf and retry. See http://crbug.com/11380 for info.
+  if (err && DnsReloadTimerHasExpired()) {
+    // When there's no network connection, _res may not be initialized by
+    // getaddrinfo. Therefore, we call res_nclose only when there are ns
+    // entries.
+    if (_res.nscount > 0)
+      res_nclose(&_res);
+    if (!res_ninit(&_res))
+      should_retry = true;
+  }
 #endif
-  int err = getaddrinfo(host.c_str(), NULL, &hints, &ai);
-  bool should_retry = false;
   // If the lookup was restricted (either by address family, or address
   // detection), and the results where all localhost of a single family,
   // maybe we should retry.  There were several bugs related to these
diff --git a/net/base/network_change_notifier.cc b/net/base/network_change_notifier.cc
index 29b983e..2eb59ad 100644
--- a/net/base/network_change_notifier.cc
+++ b/net/base/network_change_notifier.cc
@@ -90,13 +90,6 @@ void NetworkChangeNotifier::AddOnlineStateObserver(
   }
 }
 
-void NetworkChangeNotifier::AddDNSObserver(DNSObserver* observer) {
-  if (g_network_change_notifier) {
-    g_network_change_notifier->resolver_state_observer_list_->AddObserver(
-        observer);
-  }
-}
-
 void NetworkChangeNotifier::RemoveIPAddressObserver(
     IPAddressObserver* observer) {
   if (g_network_change_notifier) {
@@ -113,23 +106,13 @@ void NetworkChangeNotifier::RemoveOnlineStateObserver(
   }
 }
 
-void NetworkChangeNotifier::RemoveDNSObserver(DNSObserver* observer) {
-  if (g_network_change_notifier) {
-    g_network_change_notifier->resolver_state_observer_list_->RemoveObserver(
-        observer);
-  }
-}
-
 NetworkChangeNotifier::NetworkChangeNotifier()
     : ip_address_observer_list_(
         new ObserverListThreadSafe<IPAddressObserver>(
             ObserverListBase<IPAddressObserver>::NOTIFY_EXISTING_ONLY)),
       online_state_observer_list_(
         new ObserverListThreadSafe<OnlineStateObserver>(
-            ObserverListBase<OnlineStateObserver>::NOTIFY_EXISTING_ONLY)),
-      resolver_state_observer_list_(
-        new ObserverListThreadSafe<DNSObserver>(
-            ObserverListBase<DNSObserver>::NOTIFY_EXISTING_ONLY)) {
+            ObserverListBase<OnlineStateObserver>::NOTIFY_EXISTING_ONLY)) {
   DCHECK(!g_network_change_notifier);
   g_network_change_notifier = this;
 }
@@ -141,13 +124,6 @@ void NetworkChangeNotifier::NotifyObserversOfIPAddressChange() {
   }
 }
 
-void NetworkChangeNotifier::NotifyObserversOfDNSChange() {
-  if (g_network_change_notifier) {
-    g_network_change_notifier->resolver_state_observer_list_->Notify(
-        &DNSObserver::OnDNSChanged);
-  }
-}
-
 void NetworkChangeNotifier::NotifyObserversOfOnlineStateChange() {
   if (g_network_change_notifier) {
     g_network_change_notifier->online_state_observer_list_->Notify(
diff --git a/net/base/network_change_notifier.h b/net/base/network_change_notifier.h
index 39b9e05..dad71c3 100644
--- a/net/base/network_change_notifier.h
+++ b/net/base/network_change_notifier.h
@@ -50,22 +50,6 @@ class NET_EXPORT NetworkChangeNotifier {
     DISALLOW_COPY_AND_ASSIGN(OnlineStateObserver);
   };
 
-  class NET_EXPORT DNSObserver {
-   public:
-    virtual ~DNSObserver() {}
-
-    // Will be called when the DNS resolver of the system may have changed.
-    // This is only used on Linux currently and watches /etc/resolv.conf
-    // and /etc/hosts
-    virtual void OnDNSChanged() = 0;
-
-   protected:
-    DNSObserver() {}
-
-   private:
-    DISALLOW_COPY_AND_ASSIGN(DNSObserver);
-  };
-
   virtual ~NetworkChangeNotifier();
 
   // See the description of NetworkChangeNotifier::IsOffline().
@@ -105,7 +89,6 @@ class NET_EXPORT NetworkChangeNotifier {
   // thread), in which case it will simply do nothing.
   static void AddIPAddressObserver(IPAddressObserver* observer);
   static void AddOnlineStateObserver(OnlineStateObserver* observer);
-  static void AddDNSObserver(DNSObserver* observer);
 
   // Unregisters |observer| from receiving notifications.  This must be called
   // on the same thread on which AddObserver() was called.  Like AddObserver(),
@@ -116,7 +99,6 @@ class NET_EXPORT NetworkChangeNotifier {
   // there's no reason to use the API in this risky way, so don't do it.
   static void RemoveIPAddressObserver(IPAddressObserver* observer);
   static void RemoveOnlineStateObserver(OnlineStateObserver* observer);
-  static void RemoveDNSObserver(DNSObserver* observer);
 
   // Allow unit tests to trigger notifications.
   static void NotifyObserversOfIPAddressChangeForTests() {
@@ -131,15 +113,12 @@ class NET_EXPORT NetworkChangeNotifier {
   // tests.
   static void NotifyObserversOfIPAddressChange();
   static void NotifyObserversOfOnlineStateChange();
-  static void NotifyObserversOfDNSChange();
 
  private:
   const scoped_refptr<ObserverListThreadSafe<IPAddressObserver> >
       ip_address_observer_list_;
   const scoped_refptr<ObserverListThreadSafe<OnlineStateObserver> >
       online_state_observer_list_;
-  const scoped_refptr<ObserverListThreadSafe<DNSObserver> >
-      resolver_state_observer_list_;
 
   DISALLOW_COPY_AND_ASSIGN(NetworkChangeNotifier);
 };
diff --git a/net/base/network_change_notifier_linux.cc b/net/base/network_change_notifier_linux.cc
index 45ee139..3937de0 100644
--- a/net/base/network_change_notifier_linux.cc
+++ b/net/base/network_change_notifier_linux.cc
@@ -7,48 +7,19 @@
 #include <errno.h>
 #include <sys/socket.h>
 
-#include "base/bind.h"
-#include "base/callback_old.h"
 #include "base/compiler_specific.h"
 #include "base/eintr_wrapper.h"
-#include "base/file_util.h"
-#include "base/files/file_path_watcher.h"
 #include "base/task.h"
 #include "base/threading/thread.h"
 #include "net/base/net_errors.h"
 #include "net/base/network_change_notifier_netlink_linux.h"
 
-using ::base::files::FilePathWatcher;
-
 namespace net {
 
 namespace {
 
 const int kInvalidSocket = -1;
 
-class DNSWatchDelegate : public FilePathWatcher::Delegate {
- public:
-  explicit DNSWatchDelegate(Callback0::Type* callback)
-      : callback_(callback) {}
-  virtual ~DNSWatchDelegate() {}
-  // FilePathWatcher::Delegate interface
-  virtual void OnFilePathChanged(const FilePath& path) OVERRIDE;
-  virtual void OnFilePathError(const FilePath& path) OVERRIDE;
- private:
-  scoped_ptr<Callback0::Type> callback_;
-  DISALLOW_COPY_AND_ASSIGN(DNSWatchDelegate);
-};
-
-void DNSWatchDelegate::OnFilePathChanged(const FilePath& path) {
-  // Calls NetworkChangeNotifier::NotifyObserversOfDNSChange().
-  if (callback_.get())
-    callback_->Run();
-}
-
-void DNSWatchDelegate::OnFilePathError(const FilePath& path) {
-  LOG(ERROR) << "DNSWatchDelegate::OnFilePathError for " << path.value();
-}
-
 }  // namespace
 
 class NetworkChangeNotifierLinux::Thread
@@ -71,10 +42,6 @@ class NetworkChangeNotifierLinux::Thread
     NetworkChangeNotifier::NotifyObserversOfIPAddressChange();
   }
 
-  void NotifyObserversOfDNSChange() {
-    NetworkChangeNotifier::NotifyObserversOfDNSChange();
-  }
-
   // Starts listening for netlink messages.  Also handles the messages if there
   // are any available on the netlink socket.
   void ListenForNotifications();
@@ -91,36 +58,17 @@ class NetworkChangeNotifierLinux::Thread
   // Technically only needed for ChromeOS, but it's ugly to #ifdef out.
   ScopedRunnableMethodFactory<Thread> method_factory_;
 
-  // Used to watch for changes to /etc/resolv.conf and /etc/hosts.
-  scoped_ptr<base::files::FilePathWatcher> resolv_file_watcher_;
-  scoped_ptr<base::files::FilePathWatcher> hosts_file_watcher_;
-  scoped_refptr<DNSWatchDelegate> file_watcher_delegate_;
-
   DISALLOW_COPY_AND_ASSIGN(Thread);
 };
 
 NetworkChangeNotifierLinux::Thread::Thread()
     : base::Thread("NetworkChangeNotifier"),
       netlink_fd_(kInvalidSocket),
-      ALLOW_THIS_IN_INITIALIZER_LIST(method_factory_(this)) {
-}
+      ALLOW_THIS_IN_INITIALIZER_LIST(method_factory_(this)) {}
 
 NetworkChangeNotifierLinux::Thread::~Thread() {}
 
 void NetworkChangeNotifierLinux::Thread::Init() {
-  resolv_file_watcher_.reset(new FilePathWatcher);
-  hosts_file_watcher_.reset(new FilePathWatcher);
-  file_watcher_delegate_ = new DNSWatchDelegate(NewCallback(this,
-      &NetworkChangeNotifierLinux::Thread::NotifyObserversOfDNSChange));
-  if (!resolv_file_watcher_->Watch(
-          FilePath(FILE_PATH_LITERAL("/etc/resolv.conf")),
-          file_watcher_delegate_.get())) {
-    LOG(ERROR) << "Failed to setup watch for /etc/resolv.conf";
-  }
-  if (!hosts_file_watcher_->Watch(FilePath(FILE_PATH_LITERAL("/etc/hosts")),
-          file_watcher_delegate_.get())) {
-    LOG(ERROR) << "Failed to setup watch for /etc/hosts";
-  }
   netlink_fd_ = InitializeNetlinkSocket();
   if (netlink_fd_ < 0) {
     netlink_fd_ = kInvalidSocket;
@@ -136,10 +84,6 @@ void NetworkChangeNotifierLinux::Thread::CleanUp() {
     netlink_fd_ = kInvalidSocket;
     netlink_watcher_.StopWatchingFileDescriptor();
   }
-  // Kill watchers early to make sure they won't try to call
-  // into us via the delegate during destruction.
-  resolv_file_watcher_.reset();
-  hosts_file_watcher_.reset();
 }
 
 void NetworkChangeNotifierLinux::Thread::OnFileCanReadWithoutBlocking(int fd) {
diff --git a/net/net.gyp b/net/net.gyp
index bd6bbd2..a551c5e 100644
--- a/net/net.gyp
+++ b/net/net.gyp
@@ -82,16 +82,16 @@
         'base/default_origin_bound_cert_store.h',
         'base/directory_lister.cc',
         'base/directory_lister.h',
-        'base/dns_reloader.cc',
-        'base/dns_reloader.h',
-        'base/dns_util.cc',
-        'base/dns_util.h',
-        'base/dnsrr_resolver.cc',
-        'base/dnsrr_resolver.h',
+        'base/dns_reload_timer.cc',
+        'base/dns_reload_timer.h',
         'base/dnssec_chain_verifier.cc',
         'base/dnssec_chain_verifier.h',
         'base/dnssec_keyset.cc',
         'base/dnssec_keyset.h',
+        'base/dns_util.cc',
+        'base/dns_util.h',
+        'base/dnsrr_resolver.cc',
+        'base/dnsrr_resolver.h',
         'base/escape.cc',
         'base/escape.h',
         'base/escape_icu.cc',
@@ -209,8 +209,6 @@
         'base/ssl_info.h',
         'base/static_cookie_policy.cc',
         'base/static_cookie_policy.h',
-        'base/sys_addrinfo.h',
-        'base/sys_byteorder.h',
         'base/test_data_stream.cc',
         'base/test_data_stream.h',
         'base/test_root_certs.cc',
@@ -221,6 +219,8 @@
         'base/test_root_certs_win.cc',
         'base/transport_security_state.cc',
         'base/transport_security_state.h',
+        'base/sys_addrinfo.h',
+        'base/sys_byteorder.h',
         'base/upload_data.cc',
         'base/upload_data.h',
         'base/upload_data_stream.cc',
@@ -229,15 +229,15 @@
         'base/winsock_init.h',
         'base/winsock_util.cc',
         'base/winsock_util.h',
-        'base/x509_cert_types.cc',
-        'base/x509_cert_types.h',
-        'base/x509_cert_types_mac.cc',
         'base/x509_certificate.cc',
         'base/x509_certificate.h',
         'base/x509_certificate_mac.cc',
         'base/x509_certificate_nss.cc',
         'base/x509_certificate_openssl.cc',
         'base/x509_certificate_win.cc',
+        'base/x509_cert_types.cc',
+        'base/x509_cert_types.h',
+        'base/x509_cert_types_mac.cc',
         'base/x509_util_openssl.cc',
         'base/x509_util_openssl.h',
         'disk_cache/addr.cc',
@@ -260,6 +260,8 @@
         'disk_cache/eviction.cc',
         'disk_cache/eviction.h',
         'disk_cache/experiments.h',
+        'disk_cache/net_log_parameters.cc',
+        'disk_cache/net_log_parameters.h',
         'disk_cache/file.cc',
         'disk_cache/file.h',
         'disk_cache/file_block.h',
@@ -283,8 +285,6 @@
         'disk_cache/mem_entry_impl.h',
         'disk_cache/mem_rankings.cc',
         'disk_cache/mem_rankings.h',
-        'disk_cache/net_log_parameters.cc',
-        'disk_cache/net_log_parameters.h',
         'disk_cache/rankings.cc',
         'disk_cache/rankings.h',
         'disk_cache/sparse_control.cc',
@@ -370,8 +370,8 @@
         'http/http_auth_handler_digest.h',
         'http/http_auth_handler_factory.cc',
         'http/http_auth_handler_factory.h',
-        'http/http_auth_handler_negotiate.cc',
         'http/http_auth_handler_negotiate.h',
+        'http/http_auth_handler_negotiate.cc',
         'http/http_auth_handler_ntlm.cc',
         'http/http_auth_handler_ntlm.h',
         'http/http_auth_handler_ntlm_portable.cc',
@@ -400,12 +400,6 @@
         'http/http_network_session_peer.h',
         'http/http_network_transaction.cc',
         'http/http_network_transaction.h',
-        'http/http_proxy_client_socket.cc',
-        'http/http_proxy_client_socket.h',
-        'http/http_proxy_client_socket_pool.cc',
-        'http/http_proxy_client_socket_pool.h',
-        'http/http_proxy_utils.cc',
-        'http/http_proxy_utils.h',
         'http/http_request_headers.cc',
         'http/http_request_headers.h',
         'http/http_request_info.cc',
@@ -429,9 +423,19 @@
         'http/http_stream_parser.h',
         'http/http_transaction.h',
         'http/http_transaction_factory.h',
+        'http/url_security_manager.h',
+        'http/url_security_manager.cc',
+        'http/url_security_manager_posix.cc',
+        'http/url_security_manager_win.cc',
+        'http/http_proxy_client_socket.cc',
+        'http/http_proxy_client_socket.h',
+        'http/http_proxy_client_socket_pool.cc',
+        'http/http_proxy_client_socket_pool.h',
+        'http/http_proxy_utils.cc',
+        'http/http_proxy_utils.h',
         'http/http_util.cc',
-        'http/http_util.h',
         'http/http_util_icu.cc',
+        'http/http_util.h',
         'http/http_vary_data.cc',
         'http/http_vary_data.h',
         'http/http_version.h',
@@ -440,18 +444,14 @@
         'http/partial_data.cc',
         'http/partial_data.h',
         'http/proxy_client_socket.h',
-        'http/url_security_manager.cc',
-        'http/url_security_manager.h',
-        'http/url_security_manager_posix.cc',
-        'http/url_security_manager_win.cc',
         'ocsp/nss_ocsp.cc',
         'ocsp/nss_ocsp.h',
-        'proxy/dhcp_proxy_script_adapter_fetcher_win.cc',
-        'proxy/dhcp_proxy_script_adapter_fetcher_win.h',
         'proxy/dhcp_proxy_script_fetcher.cc',
         'proxy/dhcp_proxy_script_fetcher.h',
         'proxy/dhcp_proxy_script_fetcher_factory.cc',
         'proxy/dhcp_proxy_script_fetcher_factory.h',
+        'proxy/dhcp_proxy_script_adapter_fetcher_win.cc',
+        'proxy/dhcp_proxy_script_adapter_fetcher_win.h',
         'proxy/dhcp_proxy_script_fetcher_win.cc',
         'proxy/dhcp_proxy_script_fetcher_win.h',
         'proxy/dhcpcsvc_init_win.cc',
@@ -500,8 +500,8 @@
         'proxy/proxy_script_fetcher_impl.cc',
         'proxy/proxy_script_fetcher_impl.h',
         'proxy/proxy_server.cc',
-        'proxy/proxy_server.h',
         'proxy/proxy_server_mac.cc',
+        'proxy/proxy_server.h',
         'proxy/proxy_service.cc',
         'proxy/proxy_service.h',
         'proxy/sync_host_resolver.h',
@@ -511,8 +511,8 @@
         'socket/client_socket_factory.h',
         'socket/client_socket_handle.cc',
         'socket/client_socket_handle.h',
-        'socket/client_socket_pool.cc',
         'socket/client_socket_pool.h',
+        'socket/client_socket_pool.cc',
         'socket/client_socket_pool_base.cc',
         'socket/client_socket_pool_base.h',
         'socket/client_socket_pool_histograms.cc',
@@ -545,12 +545,12 @@
         'socket/ssl_client_socket_win.h',
         'socket/ssl_error_params.cc',
         'socket/ssl_error_params.h',
-        'socket/ssl_host_info.cc',
-        'socket/ssl_host_info.h',
         'socket/ssl_server_socket.h',
         'socket/ssl_server_socket_nss.cc',
         'socket/ssl_server_socket_nss.h',
         'socket/ssl_server_socket_openssl.cc',
+        'socket/ssl_host_info.cc',
+        'socket/ssl_host_info.h',
         'socket/stream_socket.cc',
         'socket/stream_socket.h',
         'socket/tcp_client_socket.cc',
@@ -602,10 +602,10 @@
         'spdy/spdy_websocket_stream.h',
         'third_party/mozilla_security_manager/nsKeygenHandler.cpp',
         'third_party/mozilla_security_manager/nsKeygenHandler.h',
-        'third_party/mozilla_security_manager/nsNSSCertTrust.cpp',
-        'third_party/mozilla_security_manager/nsNSSCertTrust.h',
         'third_party/mozilla_security_manager/nsNSSCertificateDB.cpp',
         'third_party/mozilla_security_manager/nsNSSCertificateDB.h',
+        'third_party/mozilla_security_manager/nsNSSCertTrust.cpp',
+        'third_party/mozilla_security_manager/nsNSSCertTrust.h',
         'third_party/mozilla_security_manager/nsPKCS12Blob.cpp',
         'third_party/mozilla_security_manager/nsPKCS12Blob.h',
         'udp/datagram_client_socket.h',
@@ -620,8 +620,8 @@
         'udp/udp_socket_libevent.h',
         'udp/udp_socket_win.cc',
         'udp/udp_socket_win.h',
-        'url_request/https_prober.cc',
         'url_request/https_prober.h',
+        'url_request/https_prober.cc',
         'url_request/url_request.cc',
         'url_request/url_request.h',
         'url_request/url_request_about_job.cc',
@@ -664,8 +664,8 @@
         'url_request/url_request_throttler_entry.cc',
         'url_request/url_request_throttler_entry.h',
         'url_request/url_request_throttler_entry_interface.h',
-        'url_request/url_request_throttler_header_adapter.cc',
         'url_request/url_request_throttler_header_adapter.h',
+        'url_request/url_request_throttler_header_adapter.cc',
         'url_request/url_request_throttler_header_interface.h',
         'url_request/url_request_throttler_manager.cc',
         'url_request/url_request_throttler_manager.h',