Revert of Last_n: instrumentation tests to verify timely snapshot deletion....

Revert of Last_n: instrumentation tests to verify timely snapshot deletion. (patchset #7 id:120001 of https://codereview.chromium.org/2833653002/ )

Reason for revert:
Likely cause of https://crbug.com/746699.

testLastNPageIsDeletedUponNavigation is flaky.

Original issue's description:
> Last_n: instrumentation tests to verify timely snapshot deletion.
>
> Adds new tests to RecentTabsTest.java to verify that offline snapshots created
> by last_n are properly deleted when successfully navigating to another page and
> upon tab closure. These actions are important to comply with privacy
> requirements for this feature.
>
> This change re-adds instrumentation tests previously committed along with a
> related bugfix [1] that were reverted due to them being flaky. It seems that the
> underlying issue causing the flakyness has been fixed [2] [3] so these should
> now work as expected.
>
> [1] https://codereview.chromium.org/2824623002/
> [2] https://bugs.chromium.org/p/chromium/issues/detail?id=592961 (restricted)
> [3] https://bugs.chromium.org/p/chromium/issues/detail?id=738490
>
> BUG=711770
>
> Review-Url: https://codereview.chromium.org/2833653002
> Cr-Commit-Position: refs/heads/master@{#487727}
> Committed: https://chromium.googlesource.com/chromium/src/+/f6fd25d5826f1a62010b08037eb50c396b05d7a2

TBR=dewittj@chromium.org,carlosk@chromium.org
# Not skipping CQ checks because original CL landed more than 1 days ago.
BUG=711770

Review-Url: https://codereview.chromium.org/2983953002
Cr-Commit-Position: refs/heads/master@{#488195}

chrome/android/java/src/org/chromium/chrome/browser/offlinepages/OfflinePageBridge.java

@@ -85,14 +85,14 @@ public class OfflinePageBridge {
         /**
          * Called when the native side of offline pages is changed due to adding, removing or
          * update an offline page.
-         * @param addedPage The in-memory representation of the page added to the offline database.
          */
         public void offlinePageAdded(OfflinePageItem addedPage) {}
 
         /**
          * Called when an offline page is deleted. This can be called as a result of
          * #checkOfflinePageMetadata().
-         * @param deletedPage Information regarding the deleted offline page.
+         * @param offlineId The offline ID of the deleted offline page.
+         * @param clientId The client supplied ID of the deleted offline page.
          */
         public void offlinePageDeleted(DeletedPageInfo deletedPage) {}
     }