predictors: Make speculative_prefetch_predictor work with PlzNavigate

chrome/browser/net/resource_prefetch_predictor_observer.cc

 // Copyright 2014 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.
 
 #include "chrome/browser/net/resource_prefetch_predictor_observer.h"
 
 #include <memory>
 #include <string>
 #include <utility>
 
@@ skipping 52 matching lines @@
     predictors::NavigationID* navigation_id,
     const content::ResourceRequestInfo::WebContentsGetter& web_contents_getter,
     const GURL& main_frame_url,
     const base::TimeTicks& creation_time) {
   DCHECK_CURRENTLY_ON(BrowserThread::UI);
   content::WebContents* web_contents = web_contents_getter.Run();
   if (!web_contents)
     return false;
   *navigation_id =
       predictors::NavigationID(web_contents, main_frame_url, creation_time);
-  return true;
+  // A WebContents might be associated with something that is not a tab.
+  // In this case tab_id will be -1 and is_valid() will return false.
+  return navigation_id->is_valid();
 }
 
 }  // namespace
 
 namespace chrome_browser_net {
 
 ResourcePrefetchPredictorObserver::ResourcePrefetchPredictorObserver(
     ResourcePrefetchPredictor* predictor)
     : predictor_(predictor->AsWeakPtr()) {
   DCHECK_CURRENTLY_ON(BrowserThread::UI);
@@ skipping 141 matching lines @@
     const base::TimeTicks& creation_time) const {
   DCHECK_CURRENTLY_ON(BrowserThread::UI);
   if (!TryToFillNavigationID(&summary->navigation_id, web_contents_getter,
                              main_frame_url, creation_time)) {
     return;
   }
   predictor_->RecordURLResponse(*summary);
 }
 
 }  // namespace chrome_browser_net