Added chrome-side support for link rel=preconnect

components/network_hints/renderer/renderer_preconnect.cc

+// Copyright 2015 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.
+
+// See header file for description of RendererPreconnect class
+
+#include "components/network_hints/renderer/renderer_preconnect.h"
+
+#include "base/bind.h"
+#include "base/location.h"
+#include "base/logging.h"
+#include "base/message_loop/message_loop.h"
+#include "components/network_hints/common/network_hints_common.h"
+#include "components/network_hints/common/network_hints_messages.h"
+#include "content/public/renderer/render_thread.h"
+
+using content::RenderThread;
+
+namespace network_hints {
+
+RendererPreconnect::RendererPreconnect()
+    : weak_factory_(this) {
+}
+
+RendererPreconnect::~RendererPreconnect() {
+}
+
+// Push URLs into the map quickly!
+void RendererPreconnect::Preconnect(const GURL &url) {
+  if (!url.is_valid())
+    return;
+
+  // If this is the first entry in the map then a task needs to be scheduled.
+  bool needs_task = url_request_count_map_.empty();
+
+  // ints will initialize to 0 automatically so incrementing will initialize
+  // new URLs to 1 or increment existing URLs (exactly the desired behavior).
+  url_request_count_map_[url]++;
+
+  if (needs_task) {
+    weak_factory_.InvalidateWeakPtrs();
+    RenderThread::Get()->GetTaskRunner()->PostDelayedTask(
+        FROM_HERE, base::Bind(&RendererPreconnect::SubmitPreconnect,
+                              weak_factory_.GetWeakPtr()),
+        base::TimeDelta::FromMilliseconds(10));
+  }
+}
+
+// Extract data from the Map, and then send it off the the Browser process
+// to be preconnected.
+void RendererPreconnect::SubmitPreconnect() {
+  DCHECK(!url_request_count_map_.empty());
+  for (const auto& entry : url_request_count_map_) {
+    RenderThread::Get()->Send(
+        new NetworkHintsMsg_Preconnect(entry.first, entry.second));
+  }
+  url_request_count_map_.clear();
+}
+
+}  // namespace network_hints