[Offline pages] Fixing crashes caused by access to offline pages marked for deletion

components/offline_pages/offline_page_model_unittest.cc

Index: components/offline_pages/offline_page_model_unittest.cc
diff --git a/components/offline_pages/offline_page_model_unittest.cc b/components/offline_pages/offline_page_model_unittest.cc
index cf661f974e11a48589a5ec61ef6b3540392e3d0f..a2df42e4b3aaba17f956ed40d87e71ff3598d2ae 100644
--- a/components/offline_pages/offline_page_model_unittest.cc
+++ b/components/offline_pages/offline_page_model_unittest.cc
@@ -600,6 +600,8 @@ TEST_F(OfflinePageModelTest, MarkPageForDeletion) {
       base::Bind(&OfflinePageModelTest::OnSavePageDone, AsWeakPtr()));
   PumpLoop();
 
+  GURL offline_url = model()->GetAllPages().begin()->GetOfflineURL();
+
   // Delete the page with undo tiggerred.
   model()->MarkPageForDeletion(
       kTestPageBookmarkId1,
@@ -610,6 +612,11 @@ TEST_F(OfflinePageModelTest, MarkPageForDeletion) {
   const std::vector<OfflinePageItem>& offline_pages = model()->GetAllPages();
   EXPECT_EQ(0UL, offline_pages.size());
 
+  EXPECT_FALSE(model()->HasOfflinePages());
+  EXPECT_EQ(nullptr, model()->GetPageByOnlineURL(kTestUrl));
+  EXPECT_EQ(nullptr, model()->GetPageByBookmarkId(kTestPageBookmarkId1));
+  EXPECT_EQ(nullptr, model()->GetPageByOfflineURL(offline_url));
+
   // Undo the deletion.
   model()->UndoPageDeletion(kTestPageBookmarkId1);
   base::RunLoop().RunUntilIdle();