This CL changes the lifespan of SSLConnectJobMessengers so that they are created only when needed,

net/socket/ssl_client_socket_pool.cc

Index: net/socket/ssl_client_socket_pool.cc
diff --git a/net/socket/ssl_client_socket_pool.cc b/net/socket/ssl_client_socket_pool.cc
index 2566f3e0ffb3a79a10e5d537759f27ae0304ce04..6347c2b0592cee1af869c8aa09deaa8e8b0a14aa 100644
--- a/net/socket/ssl_client_socket_pool.cc
+++ b/net/socket/ssl_client_socket_pool.cc
@@ -99,12 +99,8 @@ SSLConnectJobMessenger::SSLConnectJobMessenger() : weak_factory_(this) {
 }
 
 bool SSLConnectJobMessenger::CanProceed(SSLClientSocket* ssl_socket) {
-  // If the session is in the session cache, or there are no connecting
-  // sockets allow the connection to proceed.
-  if (ssl_socket->InSessionCache() || connecting_sockets_.empty()) {
-    return true;
-  }
-  return false;
+  // If there are no connecting sockets allow the connection to proceed.
+  return connecting_sockets_.empty();
 }
 
 void SSLConnectJobMessenger::MonitorConnectionResult(
@@ -169,6 +165,10 @@ void SSLConnectJobMessenger::ConnectNewLeader() {
   callback.Run();
 }
 
+bool SSLConnectJobMessenger::IsNeeded() {
+  return pending_sockets_and_callbacks_.empty() && connecting_sockets_.empty();
+}
+
 void SSLConnectJobMessenger::RunAllJobs(
     std::vector<SocketAndCallback>& pending_sockets_and_callbacks) {
   scoped_refptr<base::SingleThreadTaskRunner> task_runner =
@@ -194,6 +194,8 @@ SSLConnectJob::SSLConnectJob(const std::string& group_name,
                              HostResolver* host_resolver,
                              const SSLClientSocketContext& context,
                              SSLConnectJobMessenger* messenger,
+                             AddMessengerCallback add_messenger_callback,
+                             DeleteMessengerCallback delete_messenger_callback,
                              Delegate* delegate,
                              NetLog* net_log)
     : ConnectJob(group_name,
@@ -217,7 +219,9 @@ SSLConnectJob::SSLConnectJob(const std::string& group_name,
       io_callback_(
           base::Bind(&SSLConnectJob::OnIOComplete, base::Unretained(this))),
       messenger_(messenger),
-      weak_factory_(this) {
+      weak_factory_(this),
+      add_messenger_callback_(add_messenger_callback),
+      delete_messenger_callback_(delete_messenger_callback) {
 }
 
 SSLConnectJob::~SSLConnectJob() {}
@@ -424,17 +428,24 @@ int SSLConnectJob::DoCreateSSLSocket() {
       params_->host_and_port(),
       params_->ssl_config(),
       context_);
+
+  // Retrieve an SSLConnectJobMessenger for this connection if needed.
+  if (!ssl_socket_->InSessionCache())
+    GetMessenger(ssl_socket_->GetSessionCacheKey());
+
   return OK;
 }
 
 int SSLConnectJob::DoCheckForResume() {
   next_state_ = STATE_SSL_CONNECT;
+  if (ssl_socket_->InSessionCache())
+    return OK;
+
   if (messenger_->CanProceed(ssl_socket_.get())) {
-    if (ssl_socket_->InSessionCache())
-      return OK;
     messenger_->MonitorConnectionResult(ssl_socket_.get());
     return OK;
   }
+
   messenger_->AddPendingSocket(
       ssl_socket_.get(),
       base::Bind(&net::SSLConnectJob::ResumeSSLConnection,
@@ -453,9 +464,16 @@ int SSLConnectJob::DoSSLConnect() {
 int SSLConnectJob::DoSSLConnectComplete(int result) {
   connect_timing_.ssl_end = base::TimeTicks::Now();
 
-  if (result != OK && SSLClientSocket::GetEnableConnectJobWaiting())
-    messenger_->OnJobFailed();
-
+  if (SSLClientSocket::GetEnableConnectJobWaiting() && messenger_ != NULL) {
+    if (result != OK)
+      messenger_->OnJobFailed();
+    else {
+      // If the connection was successful, determine if the job's messenger is
+      // still needed. If not, remove the messenger.
+      if (!messenger_->IsNeeded())
+        DeleteMessenger(ssl_socket_->GetSessionCacheKey());
+    }
+  }
   SSLClientSocket::NextProtoStatus status =
       SSLClientSocket::kNextProtoUnsupported;
   std::string proto;
@@ -583,6 +601,15 @@ void SSLConnectJob::ResumeSSLConnection() {
   OnIOComplete(OK);
 }
 
+void SSLConnectJob::GetMessenger(std::string cache_key) {
+  messenger_ = add_messenger_callback_.Run(cache_key);
+}
+
+void SSLConnectJob::DeleteMessenger(std::string cache_key) {
+  delete_messenger_callback_.Run(cache_key);
+  messenger_ = NULL;
+}
+
 SSLConnectJob::State SSLConnectJob::GetInitialState(
     SSLSocketParams::ConnectionType connection_type) {
   switch (connection_type) {
@@ -616,8 +643,7 @@ SSLClientSocketPool::SSLConnectJobFactory::SSLConnectJobFactory(
       client_socket_factory_(client_socket_factory),
       host_resolver_(host_resolver),
       context_(context),
-      net_log_(net_log),
-      messenger_map_(new MessengerMap) {
+      net_log_(net_log) {
   base::TimeDelta max_transport_timeout = base::TimeDelta();
   base::TimeDelta pool_timeout;
   if (transport_pool_)
@@ -689,40 +715,49 @@ SSLClientSocketPool::~SSLClientSocketPool() {
     ssl_config_service_->RemoveObserver(this);
 }
 
-scoped_ptr<ConnectJob>
-SSLClientSocketPool::SSLConnectJobFactory::NewConnectJob(
-    const std::string& group_name,
-    const PoolBase::Request& request,
-    ConnectJob::Delegate* delegate) const {
-  SSLConnectJobMessenger* messenger;
-  std::string cache_key = SSLClientSocket::FormatSessionCacheKey(
-      request.params()->host_and_port().ToString(),
-      context_.ssl_session_cache_shard);
-  if (SSLClientSocket::GetEnableConnectJobWaiting()) {
-    MessengerMap::const_iterator it = messenger_map_->find(cache_key);
-    if (it == messenger_map_->end()) {
-      std::pair<MessengerMap::iterator, bool> iter = messenger_map_->insert(
-          MessengerMap::value_type(cache_key, new SSLConnectJobMessenger()));
+SSLConnectJobMessenger*
+SSLClientSocketPool::SSLConnectJobFactory::AddSSLConnectJobMessenger(
+    std::string cache_key) {
+  MessengerMap::const_iterator it = messenger_map_.find(cache_key);
+  if (it == messenger_map_.end()) {
+    std::pair<MessengerMap::iterator, bool> iter = messenger_map_.insert(
+        MessengerMap::value_type(cache_key, new SSLConnectJobMessenger()));
       it = iter.first;
     }
-    messenger = it->second;
-  } else {
-    messenger = NULL;
-  }
+    return it->second;
+}
+
+void SSLClientSocketPool::SSLConnectJobFactory::DeleteSSLConnectJobMessenger(
+    std::string cache_key) {
+  MessengerMap::iterator it = messenger_map_.find(cache_key);
+  delete it->second;
+  messenger_map_.erase(it);
+}
 
-  return scoped_ptr<ConnectJob>(new SSLConnectJob(group_name,
-                                                  request.priority(),
-                                                  request.params(),
-                                                  ConnectionTimeout(),
-                                                  transport_pool_,
-                                                  socks_pool_,
-                                                  http_proxy_pool_,
-                                                  client_socket_factory_,
-                                                  host_resolver_,
-                                                  context_,
-                                                  messenger,
-                                                  delegate,
-                                                  net_log_));
+scoped_ptr<ConnectJob> SSLClientSocketPool::SSLConnectJobFactory::NewConnectJob(
+    const std::string& group_name,
+    const PoolBase::Request& request,
+    ConnectJob::Delegate* delegate) {
+  return scoped_ptr<ConnectJob>(new SSLConnectJob(
+      group_name,
+      request.priority(),
+      request.params(),
+      ConnectionTimeout(),
+      transport_pool_,
+      socks_pool_,
+      http_proxy_pool_,
+      client_socket_factory_,
+      host_resolver_,
+      context_,
+      NULL,
+      base::Bind(
+          &SSLClientSocketPool::SSLConnectJobFactory::AddSSLConnectJobMessenger,
+          base::Unretained(this)),
+      base::Bind(&SSLClientSocketPool::SSLConnectJobFactory::
+                     DeleteSSLConnectJobMessenger,
+                 base::Unretained(this)),
+      delegate,
+      net_log_));
 }
 
 base::TimeDelta