When resuming downloads that were initiated using a non-default StoragePartition, the resumption request should also be created against the same StoragePartition.
Currently non-default StoragePartitions are used to isolate requests originating from WebViews within platform apps (https://developer.chrome.com/apps/tags/webview). Hence, it's possible for a download initiated from within a webview tag to end up using the wrong StoragePartition if it's resumed.
Requesting merge to M51. Baked on Canary without an incident. While the CL touches a lot of files, the non-plumbing, non-test content is small. These changes include:
* Migrating History DB schema to accommodate new field.
* Updating history code to query and store new field.
* Fixing callers of DownloadUrl() to use the correct URLRequestContextGetter.
Comment 1 by creis@chromium.org
, May 5 2016