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

chrome/browser/net/predictor_tab_helper.cc

 // 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.
 
 #include "chrome/browser/net/predictor_tab_helper.h"
 
-#include "base/command_line.h"
+#include "base/feature_list.h"
 #include "chrome/browser/net/predictor.h"
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/common/chrome_switches.h"
 #include "chrome/common/url_constants.h"
+#include "content/public/browser/navigation_handle.h"
 
 DEFINE_WEB_CONTENTS_USER_DATA_KEY(chrome_browser_net::PredictorTabHelper);
 
 namespace chrome_browser_net {
 
+namespace {
+
+// Run the preconnect predictor on all main frame and subframe navigations.
+const base::Feature kPreconnectMore{"PreconnectMoreAllFrames",
+                                    base::FEATURE_DISABLED_BY_DEFAULT};
+
+// Run the preconnect predictor on all main frame navigations. When this feature
+// is off the predictor is only run for some browser initiated navigations.
+const base::Feature kPreconnectMoreMainFrameOnly{
+    "PreconnectMoreMainFrameOnly", base::FEATURE_DISABLED_BY_DEFAULT};

[Alexei Svitkine (slow), 2016/03/21 19:42:12]

I think it would be better to use a top-level feature and use the variations
params api (go/variations-params) to control a more specific specialization in
behavior.

[Charlie Harrison, 2016/03/22 16:26:36]

Thanks for the suggestion. I was unsure of relationship between the variation
params api and the feature list api and assumed the latter subsumed the former.

+
+bool ShouldPreconnectMore() {
+  return base::FeatureList::IsEnabled(kPreconnectMore) ||
+         base::FeatureList::IsEnabled(kPreconnectMoreMainFrameOnly);
+}
+
+}  // namespace
+
 PredictorTabHelper::PredictorTabHelper(content::WebContents* web_contents)
     : content::WebContentsObserver(web_contents) {
 }
 
 PredictorTabHelper::~PredictorTabHelper() {
 }
 
+void PredictorTabHelper::DidStartNavigation(
+    content::NavigationHandle* navigation_handle) {
+  if (!ShouldPreconnectMore())
+    return;
+  if (!navigation_handle->IsInMainFrame() &&
+      !base::FeatureList::IsEnabled(kPreconnectMore)) {
+    return;
+  }
+  PreconnectUrl(navigation_handle->GetURL());
+}
+
 void PredictorTabHelper::DidStartNavigationToPendingEntry(
     const GURL& url,
     content::NavigationController::ReloadType reload_type) {
+  if (!ShouldPreconnectMore())
+    PreconnectUrl(url);
+}
+
+void PredictorTabHelper::PreconnectUrl(const GURL& url) {
   Profile* profile =
       Profile::FromBrowserContext(web_contents()->GetBrowserContext());
   chrome_browser_net::Predictor* predictor = profile->GetNetworkPredictor();
-  if (!predictor)
-    return;
-  if (url.SchemeIs(url::kHttpScheme) || url.SchemeIs(url::kHttpsScheme))
+  if (predictor && url.SchemeIsHTTPOrHTTPS())
     predictor->PreconnectUrlAndSubresources(url, GURL());
 }
 
 }  // namespace chrome_browser_net