[Prerender] LinkRelNext continues despite opt out.

Currently, the network prediction user preference allows link rel="prerender" to continue because disabling it doesn't really prevent web developers from fetching these resources by other means, like a regular fetch. The same argument should apply to link rel="next", which is what this CL does. This also affects the handling of the WebLayer network prediction setting in the same way. Bug: 1122563 Change-Id: I54517c9f12ae11f56f43a0e6c42f586492d89579 Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2379890Reviewed-by: John Abd-El-Malek <jam@chromium.org> Reviewed-by: Ryan Sturm <ryansturm@chromium.org> Commit-Queue: Mugdha Lakhani <nator@chromium.org> Cr-Commit-Position: refs/heads/master@{#802367}

[Prerender] LinkRelNext continues despite opt out.
Currently, the network prediction user preference allows link rel="prerender" to continue because disabling it doesn't really prevent web developers from fetching these resources by other means, like a regular fetch. The same argument should apply to link rel="next", which is what this CL does. This also affects the handling of the WebLayer network prediction setting in the same way. Bug: 1122563 Change-Id: I54517c9f12ae11f56f43a0e6c42f586492d89579 Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2379890Reviewed-by: John Abd-El-Malek <jam@chromium.org> Reviewed-by: Ryan Sturm <ryansturm@chromium.org> Commit-Queue: Mugdha Lakhani <nator@chromium.org> Cr-Commit-Position: refs/heads/master@{#802367}
678e8ff8 · Mugdha Lakhani · Commit Bot · df295c8f · 678e8ff8 · 678e8ff8
Commit 678e8ff8 authored Aug 27, 2020 by Mugdha Lakhani Committed by Commit Bot Aug 27, 2020
4 changed files
--- a/components/prerender/browser/prerender_manager.cc
+++ b/components/prerender/browser/prerender_manager.cc
@@ -509,12 +509,14 @@ bool PrerenderManager::IsLowEndDevice() const {
 bool PrerenderManager::IsPredictionEnabled(Origin origin) {
  DCHECK_CURRENTLY_ON(content::BrowserThread::UI);

-  // <link rel=prerender> origins ignore the network state and the privacy
+  // <link rel=prerender> and <link rel=next> origins ignore the network state
+  // and the privacy
  // settings. Web developers should be able prefetch with all possible privacy
  // settings. This would avoid web devs coming up with creative ways to
  // prefetch in cases they are not allowed to do so.
  if (origin == ORIGIN_LINK_REL_PRERENDER_SAMEDOMAIN ||
-      origin == ORIGIN_LINK_REL_PRERENDER_CROSSDOMAIN) {
+      origin == ORIGIN_LINK_REL_PRERENDER_CROSSDOMAIN ||
+      origin == ORIGIN_LINK_REL_NEXT) {
    return true;
  }


--- a/weblayer/browser/no_state_prefetch/no_state_prefetch_browsertest.cc
+++ b/weblayer/browser/no_state_prefetch/no_state_prefetch_browsertest.cc
@@ -81,9 +81,6 @@ class NoStatePrefetchBrowserTest : public WebLayerBrowserTest {
    if (request.GetURL().path().find("prefetch_meta.js") != std::string::npos) {
      script_executed_ = true;
    }
-    if (request.GetURL().path().find("alert.html") != std::string::npos) {
-      link_rel_next_started_ = true;
-    }

    // The default handlers will take care of this request.
    return nullptr;
@@ -106,7 +103,6 @@ class NoStatePrefetchBrowserTest : public WebLayerBrowserTest {

  std::unique_ptr<base::RunLoop> prerendered_page_fetched_;
  std::unique_ptr<base::RunLoop> script_resource_fetched_;
-  bool link_rel_next_started_ = false;
  bool script_fetched_ = false;
  bool script_executed_ = false;
  std::string purpose_header_value_;
@@ -199,14 +195,14 @@ IN_PROC_BROWSER_TEST_F(NoStatePrefetchBrowserTest,
  prerendered_page_fetched_->Run();
 }

-// link-rel="next" doesn't happen when NoStatePrefetch has been disabled.
+// link-rel="next" happens even when NoStatePrefetch has been disabled.
 IN_PROC_BROWSER_TEST_F(NoStatePrefetchBrowserTest, LinkRelNextWithNSPDisabled) {
  GetProfile()->SetBooleanSetting(SettingType::NETWORK_PREDICTION_ENABLED,
                                  false);
-  NavigateToPageAndWaitForTitleChange(
-      GURL(https_server_->GetURL("/parent_page.html")),
-      base::ASCIIToUTF16("Parent Page"));
-  EXPECT_FALSE(link_rel_next_started_);
+  NavigateAndWaitForCompletion(
+      GURL(https_server_->GetURL("/link_rel_next_parent.html")), shell());
+
+  prerendered_page_fetched_->Run();
 }

 }  // namespace weblayer
\ No newline at end of file
--- a/weblayer/test/data/link_rel_next_parent.html
+++ b/weblayer/test/data/link_rel_next_parent.html
+<html>
+<body>
+This page will prerender something.
+<link rel="next" href="/prerendered_page.html">
+</body>
+
+<!-- Order is important for tests. -->
+<head><title>Parent Page</title></head>
+</html>
--- a/weblayer/test/data/parent_page.html
+++ b/weblayer/test/data/parent_page.html
@@ -2,7 +2,6 @@
 <body>
 This page will prerender something.
 <link rel="prerender" href="/prerendered_page.html">
-<link rel="next" href="/alert.html">
 </body>

 <!-- Order is important for tests. -->