Implement WebPrescientNetworking to trigger preconnect from Blink

chrome/common/render_messages.h

 // Copyright (c) 2012 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.
 
 // Multiply-included file, no traditional include guard.
 #include <map>
 #include <set>
 #include <string>
 #include <vector>
 
@@ skipping 626 matching lines @@
 // Sends back stats about the V8 heap.
 IPC_MESSAGE_CONTROL2(ChromeViewHostMsg_V8HeapStats,
                      int /* size of heap (allocated from the OS) */,
                      int /* bytes in use */)
 
 // Request for a DNS prefetch of the names in the array.
 // NameList is typedef'ed std::vector<std::string>
 IPC_MESSAGE_CONTROL1(ChromeViewHostMsg_DnsPrefetch,
                      std::vector<std::string> /* hostnames */)
 
+// Request for preconnect to host providing resource specified by URL
+IPC_MESSAGE_CONTROL1(ChromeViewHostMsg_Preconnect,
+                     GURL /* preconnect target url */)
+
 // Notifies when a plugin couldn't be loaded because it's outdated.
 IPC_MESSAGE_ROUTED2(ChromeViewHostMsg_BlockedOutdatedPlugin,
                     int /* placeholder ID */,
                     std::string /* plug-in group identifier */)
 
 // Notifies when a plugin couldn't be loaded because it requires
 // user authorization.
 IPC_MESSAGE_ROUTED2(ChromeViewHostMsg_BlockedUnauthorizedPlugin,
                     string16 /* name */,
                     std::string /* plug-in group identifier */)
@@ skipping 105 matching lines @@
 // previous SetCookie message to be processed.
 IPC_SYNC_MESSAGE_ROUTED2_1(ChromeViewHostMsg_GetCookies,
                            GURL /* url */,
                            GURL /* first_party_for_cookies */,
                            std::string /* cookies */)
 
 // Provide the browser process with current renderer framerate.
 IPC_MESSAGE_CONTROL2(ChromeViewHostMsg_FPS,
                      int /* routing id */,
                      float /* frames per second */)