Load live version when reloading an offline page on connected network

chrome/browser/android/offline_pages/offline_page_tab_helper.cc

 // Copyright 2016 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/android/offline_pages/offline_page_tab_helper.h"
 
 #include "base/bind.h"
 #include "base/logging.h"
 #include "base/memory/ptr_util.h"
 #include "chrome/browser/android/offline_pages/offline_page_request_job.h"
@@ skipping 19 matching lines @@
 }
 
 OfflinePageTabHelper::~OfflinePageTabHelper() {}
 
 void OfflinePageTabHelper::DidStartNavigation(
     content::NavigationHandle* navigation_handle) {
   // Skips non-main frame.
   if (!navigation_handle->IsInMainFrame())
     return;
 
+  // If the navigation is referencing fragment (synchronous navigation could
+  // only be referencing fragment navigation or pushState/popState navigation,
+  // while the latter is unlikely because offline page disables Javascript
+  // execution), do not reset out cached offline info.
+  if (navigation_handle->IsSynchronousNavigation())

[Dmitry Titov, 2016/09/17 02:22:54]

As discussed, lets keep the IsSamePage() check in DidFinishNamvigation, and not
use IsSynchronousNavigation. 

So I think the best approach here is:
0. Have provisional values for page, header, is_offline_preview.
1. Clear provisional values in DidStartNavigation
2. Most of the time (but not always) Interceptor will chime in with
SetOfflinePage and set provisional values
3. In DidFinishNavigation, if not IsSamePage, do real_values <-
provisional-values.

This works in many combinations when some callbacks are missing/repeated, and is
more direct.

[jianli, 2016/09/19 21:29:05]

We also need to clear the real values here because otherwise the following bug
will be hit:
1) Open a downloaded page on connected network. The offline indicator should be
shown.
2) Manually type any other URL of a web site that could take a while to load.
The offline indicator will not be reset during loading.

+    return;
+
   // This is a new navigation so we can invalidate any previously scheduled
   // operations.
   weak_ptr_factory_.InvalidateWeakPtrs();
 
   provisional_offline_page_ = nullptr;
+  offline_page_ = nullptr;
+  offline_header_.Clear();
   is_offline_preview_ = false;
   reloading_url_on_net_error_ = false;
 }
 
 void OfflinePageTabHelper::DidFinishNavigation(
     content::NavigationHandle* navigation_handle) {
   // Skips non-main frame.
   if (!navigation_handle->IsInMainFrame())
     return;
 
   if (!navigation_handle->HasCommitted())
     return;
 
-  if (navigation_handle->IsSamePage()) {
+  if (navigation_handle->IsSynchronousNavigation())
     return;
-  }
 
   offline_page_ = std::move(provisional_offline_page_);
   provisional_offline_page_ = nullptr;
 
   // We might be reloading the URL in order to fetch the offline page.
   // * If successful, nothing to do.
   // * Otherwise, we're hitting error again. Bail out to avoid loop.
   if (reloading_url_on_net_error_)
     return;
 
@@ skipping 43 matching lines @@
         OfflinePageRequestJob::AggregatedRequestResult::
             PAGE_NOT_FOUND_ON_FLAKY_NETWORK);
     return;
   }
 
   reloading_url_on_net_error_ = true;
 
   // Reloads the page with extra header set to force loading the offline page.
   content::NavigationController::LoadURLParams load_params(offline_page->url);
   load_params.transition_type = ui::PAGE_TRANSITION_RELOAD;
-  load_params.extra_headers = kOfflinePageHeader;
-  load_params.extra_headers += ":";
-  load_params.extra_headers += kOfflinePageHeaderReasonKey;
-  load_params.extra_headers += "=";
-  load_params.extra_headers += kOfflinePageHeaderReasonValueDueToNetError;
+  OfflinePageHeader offline_header;
+  offline_header.reason = OfflinePageHeader::Reason::NET_ERROR;
+  load_params.extra_headers = offline_header.GetCompleteHeaderString();
   web_contents()->GetController().LoadURLWithParams(load_params);
 }
 
 // This is a callback from network request interceptor. It happens between
 // DidStartNavigation and DidFinishNavigation calls on this tab helper.
-void OfflinePageTabHelper::SetOfflinePage(const OfflinePageItem& offline_page,
-                                          bool is_offline_preview) {
+void OfflinePageTabHelper::SetOfflinePage(
+    const OfflinePageItem& offline_page,
+    const OfflinePageHeader& offline_header,
+    bool is_offline_preview) {
   provisional_offline_page_ = base::MakeUnique<OfflinePageItem>(offline_page);
+  offline_header_ = offline_header;
   is_offline_preview_ = is_offline_preview;
 }
 
 const OfflinePageItem* OfflinePageTabHelper::GetOfflinePageForTest() const {
   return provisional_offline_page_.get();
 }
 
 }  // namespace offline_pages