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

chrome/browser/net/predictor_tab_helper.h

Index: chrome/browser/net/predictor_tab_helper.h
diff --git a/chrome/browser/net/predictor_tab_helper.h b/chrome/browser/net/predictor_tab_helper.h
index 4d95ba0d2b56d9635856a557fda4c1ae320d74a9..7480b17b85e91e406ea9a8777e135bd386f881d4 100644
--- a/chrome/browser/net/predictor_tab_helper.h
+++ b/chrome/browser/net/predictor_tab_helper.h
@@ -11,6 +11,10 @@
 #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
@@ -19,7 +23,9 @@ class 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;
@@ -28,6 +34,17 @@ class PredictorTabHelper
   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);
 };