Support restricting browsing data removal for downloads by origin.

content/public/browser/download_manager.h

Index: content/public/browser/download_manager.h
diff --git a/content/public/browser/download_manager.h b/content/public/browser/download_manager.h
index 74cb77d6d4da6560517efca3dfff1fec8c1a8a39..e50bea2392bfbc5db4ace1e615031353c31c648c 100644
--- a/content/public/browser/download_manager.h
+++ b/content/public/browser/download_manager.h
@@ -44,6 +44,10 @@
 
 class GURL;
 
+namespace url {
+class Origin;
+}
+
 namespace content {
 
 class BrowserContext;
@@ -110,10 +114,12 @@ class CONTENT_EXPORT DownloadManager : public base::SupportsUserData::Data {
       scoped_ptr<ByteStreamReader> stream,
       const DownloadUrlParameters::OnStartedCallback& on_started) = 0;
 
-  // Remove downloads after remove_begin (inclusive) and before remove_end
-  // (exclusive). You may pass in null Time values to do an unbounded delete
-  // in either direction.
-  virtual int RemoveDownloadsBetween(base::Time remove_begin,
+  // Remove downloads which are same-origin with the given origin, are after
+  // remove_begin (inclusive), and before remove_end (exclusive). You may pass
+  // in null Time values to do an unbounded delete in either direction. A
+  // unique origin causes all origins to be removed.

[Randy Smith (Not in Mondays), 2015/08/03 19:09:30]

I'm uncomfortable with using unique origins to indicate "all origins".  Could
you instead add a separate interface (maybe |RemoveDownloadByOrigin|) that just
removes origins that match the passed origin without the extra semantics for
unique origins?

[Timo Reimann, 2015/08/03 20:09:32]

Sounds legitimate; especially since mkwst raised similar concerns already.

Internally, I guess we'd want |RemoveDownloadsBetween| and
|RemoveDownloadsByOrigin| to be based on the same implementation with some means
to indicate absence/presence of an origin? If so, I suppose a simple pointer
(with NULL being absence and non-NULL being presence) could fit the purpose
unless we want to have something more sophisticated.

+  virtual int RemoveDownloadsBetween(const url::Origin& origin_to_clear,
+                                     base::Time remove_begin,
                                      base::Time remove_end) = 0;
 
   // Remove downloads will delete all downloads that have a timestamp that is