Reland r187230: Implement the Stream registry in content

Reland r187230: Implement the Stream registry in content

This fixes the memory leaks introduced by the original CL.

BUG=171585
Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=187777

[Zachary Kuznia, 2013-03-11 12:41:14]

I reverted the last patch, since it caused HeapCheck and Valgrind errors.  This
patch resolves those issues.

I uploaded the difference between the original patch and this one here:
https://codereview.chromium.org/12615004/

Please take another look.

Thanks,
-Zach

[Zachary Kuznia, 2013-03-11 15:43:25]

FYI, the changes I needed to make are just using weak pointers for connecting to
ByteStream in stream.cc/h, and add back the custom deleter to StreamContext. 
The reason the custom deleter is needed is that there are many tests that
trigger the creation of the StreamContext that do not have an IO thread.  With
the default DeleteOnIOThread, these become leaks.

[kinuko, 2013-03-12 03:39:14]

The diff lgtm

[darin (slow to review), 2013-03-12 04:08:01]

LGTM2

[commit-bot: I haz the power, 2013-03-12 23:44:58]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/[email protected]/12637006/51001

[commit-bot: I haz the power, 2013-03-13 04:34:21]

Change committed as 187777