[bfcache] Do not cache offline pages.

Do not put offline pages in back-forward cache as if we have network,
we should reload the full page and if there is no network, offline page
will be reloaded.

R=jianli@chromium.org
CC=bfcache-bugs@chromium.org
BUG=1001087

Change-Id: I2dd9fea312a4ced6355ad3aaa052aeb44ca99779
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1837625Reviewed-by: Jian Li <jianli@chromium.org>
Reviewed-by: Kouhei Ueno <kouhei@chromium.org>
Commit-Queue: Alexander Timin <altimin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#704106}

chrome/browser/offline_pages/offline_page_tab_helper.cc

@@ -30,6 +30,7 @@
 #include "components/offline_pages/core/prefetch/offline_metrics_collector.h"
 #include "components/offline_pages/core/prefetch/prefetch_service.h"
 #include "components/offline_pages/core/request_header/offline_page_header.h"
+#include "content/public/browser/back_forward_cache.h"
 #include "content/public/browser/browser_thread.h"
 #include "content/public/browser/navigation_controller.h"
 #include "content/public/browser/navigation_entry.h"
@@ -184,6 +185,15 @@ void OfflinePageTabHelper::DidFinishNavigation(
   if (navigation_handle->IsSameDocument())
     return;
 
+  if (offline_info_.IsValid()) {
+    // Do not store the offline page we are navigating away from in bfcache.
+    // If we managed to establish a network connection, we should reload the
+    // full page on back navigation. If not, offline page is fast to load,
+    // so back-forward cache is not going to be useful here.
+    content::BackForwardCache::DisableForRenderFrameHost(
+        navigation_handle->GetPreviousRenderFrameHostId(), "OfflinePage");
+  }
+
   // This is a new navigation so we can invalidate any previously scheduled
   // operations.
   weak_ptr_factory_.InvalidateWeakPtrs();

chrome/browser/offline_pages/offline_page_tab_helper_unittest.cc

@@ -19,7 +19,9 @@
 #include "components/offline_pages/core/prefetch/offline_metrics_collector.h"
 #include "components/offline_pages/core/prefetch/prefetch_service.h"
 #include "components/offline_pages/core/prefetch/prefetch_service_test_taco.h"
+#include "content/public/browser/render_process_host.h"
 #include "content/public/browser/web_contents.h"
+#include "content/public/test/back_forward_cache_util.h"
 #include "content/public/test/navigation_simulator.h"
 #include "content/public/test/test_renderer_host.h"
 #include "content/public/test/web_contents_tester.h"
@@ -425,5 +427,24 @@ TEST_F(OfflinePageTabHelperTest, AbortedNavigationDoesNotResetOfflineInfo) {
   EXPECT_TRUE(tab_helper()->offline_page());
 }
 
+TEST_F(OfflinePageTabHelperTest, OfflinePageIsNotStoredInBackForwardCache) {
+  content::BackForwardCacheDisabledTester back_forward_cache_tester;
+
+  CreateNavigationSimulator(kTestPageUrl);
+  navigation_simulator()->Start();
+
+  SimulateOfflinePageLoad(kTestPageUrl, kTestMhtmlCreationTime,
+                          MHTMLLoadResult::kSuccess);
+
+  int process_id = web_contents()->GetMainFrame()->GetProcess()->GetID();
+  int main_frame_id = web_contents()->GetMainFrame()->GetRoutingID();
+
+  // Navigate away.
+  content::NavigationSimulator::NavigateAndCommitFromBrowser(web_contents(),
+                                                             kTestPageUrl);
+  EXPECT_TRUE(back_forward_cache_tester.IsDisabledForFrameWithReason(
+      process_id, main_frame_id, "OfflinePage"));
+}
+
 }  // namespace
 }  // namespace offline_pages