[Background Fetch] Fix download notification bugs.

- Set is_resumable in the OfflineItem to true so that paused downloads
can be resumed.
- Fix deallocated memory access in the Abort workflow which was causing
the browser to crash.

Change-Id: I2369ffe517796c245b6d3351e4d90aa6b4a1510b
Reviewed-on: https://chromium-review.googlesource.com/1253624
Commit-Queue: Rayan Kanso <rayankans@chromium.org>
Reviewed-by: Peter Beverloo <peter@chromium.org>
Cr-Commit-Position: refs/heads/master@{#595443}

chrome/browser/background_fetch/background_fetch_browsertest.cc

@@ -506,6 +506,7 @@ IN_PROC_BROWSER_TEST_F(BackgroundFetchBrowserTest,
   EXPECT_EQ(offline_item.title, GetExpectedTitle(kSingleFileDownloadTitle));
   EXPECT_EQ(offline_item.filter, OfflineItemFilter::FILTER_OTHER);
   EXPECT_TRUE(offline_item.is_transient);
+  EXPECT_TRUE(offline_item.is_resumable);
   EXPECT_FALSE(offline_item.is_suggested);
   EXPECT_FALSE(offline_item.is_off_the_record);
 
@@ -517,7 +518,6 @@ IN_PROC_BROWSER_TEST_F(BackgroundFetchBrowserTest,
   // Change-detector tests for values we might want to provide or change.
   EXPECT_TRUE(offline_item.description.empty());
   EXPECT_TRUE(offline_item.page_url.is_empty());
-  EXPECT_FALSE(offline_item.is_resumable);
   EXPECT_FALSE(offline_item.is_off_the_record);
 }
 

chrome/browser/background_fetch/background_fetch_delegate_impl.cc

@@ -112,8 +112,9 @@ void BackgroundFetchDelegateImpl::JobDetails::UpdateOfflineItem() {
         base::StringPrintf("%s (%s)", fetch_description->title.c_str(),
                            fetch_description->origin.Serialize().c_str());
   }
-  // TODO(delphick): Figure out what to put in offline_item.description.
+
   offline_item.is_transient = true;
+  offline_item.is_resumable = true;
 
   using OfflineItemState = offline_items_collection::OfflineItemState;
   if (cancelled) {
@@ -519,11 +520,14 @@ void BackgroundFetchDelegateImpl::FailFetch(const std::string& job_unique_id) {
 
 void BackgroundFetchDelegateImpl::CancelDownload(
     const offline_items_collection::ContentId& id) {
-  Abort(id.id);
+  // Save a copy before Abort() deletes the reference.
+  const std::string unique_id = id.id;
+  Abort(unique_id);
 
   if (client()) {
     client()->OnJobCancelled(
-        id.id, blink::mojom::BackgroundFetchFailureReason::CANCELLED_FROM_UI);
+        unique_id,
+        blink::mojom::BackgroundFetchFailureReason::CANCELLED_FROM_UI);
   }
 }