[reland] Change net's predictor_tab_helper to use the new content Navigation API

chrome/browser/net/predictor_tab_helper.h

 // Copyright 2013 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 CHROME_BROWSER_NET_PREDICTOR_TAB_HELPER_H_
 #define CHROME_BROWSER_NET_PREDICTOR_TAB_HELPER_H_
 
 #include "base/macros.h"
 #include "content/public/browser/notification_observer.h"
 #include "content/public/browser/notification_registrar.h"
 #include "content/public/browser/web_contents_observer.h"
 #include "content/public/browser/web_contents_user_data.h"
 
+namespace content {
+class NavigationHandle;
+}
+
 namespace chrome_browser_net {
 
 class PredictorTabHelper
     : public content::WebContentsObserver,
       public content::WebContentsUserData<PredictorTabHelper> {
  public:
   ~PredictorTabHelper() override;
 
-  // content::WebContentsObserver implementation
+  // content::WebContentsObserver:
+  void DidStartNavigation(
+      content::NavigationHandle* navigation_handle) override;
   void DidStartNavigationToPendingEntry(
       const GURL& url,
       content::NavigationController::ReloadType reload_type) override;
 
  private:
   explicit PredictorTabHelper(content::WebContents* web_contents);
   friend class content::WebContentsUserData<PredictorTabHelper>;
 
+  void PreconnectUrl(const GURL& url);
+
+  // This boolean is set to true after a call to
+  // DidStartNavigationToPendingEntry, which fires off predictive preconnects.
+  // This ensures that the resulting call to DidStartNavigation does not
+  // duplicate these preconnects. The tab helper spawns preconnects on the
+  // navigation to the pending entry because DidStartNavigation is called after
+  // render process spawn (pre-PlzNavigate), which can take substantial time
+  // especially on Android.
+  bool predicted_from_pending_entry_;
+
   DISALLOW_COPY_AND_ASSIGN(PredictorTabHelper);
 };
 
 }  // namespace chrome_browser_net
 
 #endif  // CHROME_BROWSER_NET_PREDICTOR_TAB_HELPER_H_