Link disabled offline pages tests with respective crbug issues

To make it easier to track the reason why tests are disabled one should
add links from the disabled test to the issue in crbug that explains why
they were disabled. This adds missing links from a few offline pages
tests.

TBR=dimich@chromium.org

Bug: 830282, 870295
Change-Id: I1de64bfaf41211fd4585ec9733e6c80c338d4526
Reviewed-on: https://chromium-review.googlesource.com/1161441Reviewed-by: Carlos Knippschild <carlosk@chromium.org>
Commit-Queue: Carlos Knippschild <carlosk@chromium.org>
Cr-Commit-Position: refs/heads/master@{#580381}

chrome/android/javatests/src/org/chromium/chrome/browser/offlinepages/prefetch/PrefetchBackgroundTaskTest.java

@@ -284,7 +284,7 @@ public class PrefetchBackgroundTaskTest {
 
     @Test
     @SmallTest
-    @DisabledTest
+    @DisabledTest(message = "https://crbug.com/870295")
     public void testSuspend() throws Exception {
         PrefetchBackgroundTask.skipConditionCheckingForTesting();
         scheduleTask(0);

chrome/browser/offline_pages/offline_page_request_handler_unittest.cc

@@ -1638,6 +1638,7 @@ TYPED_TEST(OfflinePageRequestHandlerTest,
                       AGGREGATED_REQUEST_RESULT_MAX);
 }
 
+// TODO(https://crbug.com/830282): Flaky on "Marshmallow Phone Tester (rel)".
 TYPED_TEST(OfflinePageRequestHandlerTest,
            DISABLED_LoadMostRecentlyCreatedOfflinePage) {
   this->SimulateHasNetworkConnectivity(false);
@@ -1703,6 +1704,7 @@ TYPED_TEST(OfflinePageRequestHandlerTest, FailToLoadByOfflineIDOnUrlMismatch) {
                       PAGE_NOT_FOUND_ON_CONNECTED_NETWORK);
 }
 
+// TODO(https://crbug.com/830282): Flaky on "Marshmallow Phone Tester (rel)".
 TYPED_TEST(OfflinePageRequestHandlerTest,
            DISABLED_LoadOfflinePageForUrlWithFragment) {
   this->SimulateHasNetworkConnectivity(false);