HTTPS Previews: Load original page on a reload

This allows the previews decision logic to run again.

This is tested by checking the existance of server_lite_page_info which
is not persisted across reloads. Note: forward/back navigations also
do not persist server_lite_page_info.

Bug: 864665
Change-Id: Ibe5d1b698a0f790474992967561ecdd81ac348f4
Reviewed-on: https://chromium-review.googlesource.com/c/1352823Reviewed-by: Tarun Bansal <tbansal@chromium.org>
Commit-Queue: Robert Ogden <robertogden@chromium.org>
Cr-Commit-Position: refs/heads/master@{#611601}

chrome/browser/previews/previews_lite_page_browsertest.cc

@@ -271,6 +271,15 @@ class PreviewsLitePageServerBrowserTest : public InProcessBrowserTest {
 
     content::NavigationEntry* entry =
         GetWebContents()->GetController().GetVisibleEntry();
+
+    // server_lite_page_info does not exist on forward/back navigations.
+    if (!(entry->GetTransitionType() & ui::PAGE_TRANSITION_FORWARD_BACK)) {
+      EXPECT_TRUE(previews_data->server_lite_page_info());
+      EXPECT_NE(
+          previews_data->server_lite_page_info()->original_navigation_start,
+          base::TimeTicks());
+    }
+
     EXPECT_EQ(content::PAGE_TYPE_NORMAL, entry->GetPageType());
     const GURL virtual_url = entry->GetVirtualURL();
 
@@ -803,6 +812,19 @@ IN_PROC_BROWSER_TEST_F(PreviewsLitePageServerBrowserTest,
 
   GetWebContents()->GetController().Reload(content::ReloadType::NORMAL, false);
   VerifyPreviewLoaded();
+
+  // Set the ECT so that a preview won't be triggered on the reload.
+  g_browser_process->network_quality_tracker()
+      ->ReportEffectiveConnectionTypeForTesting(
+          net::EFFECTIVE_CONNECTION_TYPE_4G);
+
+  GetWebContents()->GetController().Reload(content::ReloadType::NORMAL, false);
+  VerifyPreviewNotLoaded();
+
+  // Reset ECT for future tests.
+  g_browser_process->network_quality_tracker()
+      ->ReportEffectiveConnectionTypeForTesting(
+          net::EFFECTIVE_CONNECTION_TYPE_2G);
 }
 
 IN_PROC_BROWSER_TEST_F(PreviewsLitePageServerBrowserTest,

chrome/browser/previews/previews_lite_page_navigation_throttle.cc

@@ -543,6 +543,31 @@ PreviewsLitePageNavigationThrottle::MaybeNavigateToPreview() const {
 
 content::NavigationThrottle::ThrottleCheckResult
 PreviewsLitePageNavigationThrottle::WillStartRequest() {
+  // Check if the user is trying to navigate to a valid previews URL in the form
+  // of a reload. In such a case, cancel the navigation and start a new one to
+  // the original URL instead. We might trigger this preview again, but if so
+  // there will be a server_lite_page_info associated with it.
+  std::string original_url;
+  if (previews::ExtractOriginalURLFromLitePageRedirectURL(
+          navigation_handle()->GetURL(), &original_url) &&
+      navigation_handle()->GetReloadType() == content::ReloadType::NORMAL) {
+    // Don't use |LoadAndBypass| because we might not want to bypass.
+    WebContentsLifetimeHelper::CreateForWebContents(
+        navigation_handle()->GetWebContents());
+    WebContentsLifetimeHelper* helper =
+        WebContentsLifetimeHelper::FromWebContents(
+            navigation_handle()->GetWebContents());
+
+    base::PostTaskWithTraits(
+        FROM_HERE, {content::BrowserThread::UI},
+        base::BindOnce(&WebContentsLifetimeHelper::PostNewNavigation,
+                       helper->GetWeakPtr(),
+                       MakeOpenURLParams(navigation_handle(),
+                                         GURL(original_url), std::string()),
+                       GetOrCreateServerLitePageInfo(navigation_handle())));
+    return content::NavigationThrottle::CANCEL;
+  }
+
   MaybeReportNavigationRestartPenalty(navigation_handle());
   return MaybeNavigateToPreview();
 }