Make HttpNetworkSession::DumpMemoryStats attribute memory usage correctly

This CL creates an empty MemoryAllocatorDump under URLRequestContext
so AddOwnershipEdge can attribute memory correctly between
URLRequestContexts. See the following doc for more details on why it
is needed.

https://docs.google.com/document/d/1-dmr_dVgO090Y5_3K9itjsE0MsBTmbqwovu6lup1i14/edit

BUG=669108
Committed: https://crrev.com/2a2468bdec640adaa6a08f9ca1cfe465e56e7600
Cr-Commit-Position: refs/heads/master@{#441466}

[xunjieli, 2016-12-06 21:11:21]

Description was changed from

==========
TEMP HttpNetworkSession Option 2

BUG=
==========

to

==========
TEMP HttpNetworkSession Option 2

BUG=
==========

[xunjieli, 2016-12-06 21:16:04]

Patchset #1 (id:1) has been deleted

[xunjieli, 2016-12-15 19:01:04]

Description was changed from

==========
TEMP HttpNetworkSession Option 2

BUG=
==========

to

==========
HttpNetworkSession::DumpMemoryStats attribute memory usage correctly

This CL creates an empty MemoryAllocatorDump under URLRequestContext
so AddOwnershipEdge can attribute memory correctly between 
URLRequestContexts. See the following doc for more details on why it
is needed.

https://docs.google.com/document/d/1-dmr_dVgO090Y5_3K9itjsE0MsBTmbqwovu6lup1i...

BUG=669108
==========

[xunjieli, 2016-12-15 19:01:16]

Patchset #1 (id:20001) has been deleted

[xunjieli, 2016-12-15 19:05:36]

xunjieli@chromium.org changed reviewers:
+ primiano@chromium.org, ssid@chromium.org

[xunjieli, 2016-12-15 19:05:36]

This is to follow up on the discussion at
https://docs.google.com/document/d/1-dmr_dVgO090Y5_3K9itjsE0MsBTmbqwovu6lup1i....

I found that the aliasing indeed doesn't work correctly once I start adding more
stuff under net/url_request_context.


PTAL.

[xunjieli, 2016-12-15 19:05:47]

Description was changed from

==========
HttpNetworkSession::DumpMemoryStats attribute memory usage correctly

This CL creates an empty MemoryAllocatorDump under URLRequestContext
so AddOwnershipEdge can attribute memory correctly between 
URLRequestContexts. See the following doc for more details on why it
is needed.

https://docs.google.com/document/d/1-dmr_dVgO090Y5_3K9itjsE0MsBTmbqwovu6lup1i...

BUG=669108
==========

to

==========
This CL creates an empty MemoryAllocatorDump under URLRequestContext
so AddOwnershipEdge can attribute memory correctly between 
URLRequestContexts. See the following doc for more details on why it
is needed.

https://docs.google.com/document/d/1-dmr_dVgO090Y5_3K9itjsE0MsBTmbqwovu6lup1i...

BUG=669108
==========

[xunjieli, 2016-12-15 19:06:58]

The CQ bit was checked by xunjieli@chromium.org to run a CQ dry run

[commit-bot: I haz the power, 2016-12-15 19:07:12]

Dry run: CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2016-12-15 20:44:06]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2016-12-15 20:44:07]

Dry run: This issue passed the CQ dry run.

[xunjieli, 2017-01-03 00:44:41]

Primiano, Sid: A friendly ping!

[xunjieli, 2017-01-04 18:49:14]

On 2017/01/03 00:44:41, xunjieli wrote:
> Primiano, Sid: A friendly ping!

A friendly ping! 
(I have more things lined up for net MDP that are blocked on this)

[ssid, 2017-01-04 20:08:11]

lgtm thanks

[xunjieli, 2017-01-04 20:08:29]

The CQ bit was checked by xunjieli@chromium.org

[commit-bot: I haz the power, 2017-01-04 20:09:01]

CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2017-01-04 21:17:38]

CQ is committing da patch.

Bot data: {"patchset_id": 60001, "attempt_start_ts": 1483560509088090,
"parent_rev": "830b4269aa8abb9cc03e928c5528b81bf1f84deb", "commit_rev":
"e9e34e35965f332978cebb1bd89a36feef049199"}

[commit-bot: I haz the power, 2017-01-04 21:18:57]

Description was changed from

==========
This CL creates an empty MemoryAllocatorDump under URLRequestContext
so AddOwnershipEdge can attribute memory correctly between 
URLRequestContexts. See the following doc for more details on why it
is needed.

https://docs.google.com/document/d/1-dmr_dVgO090Y5_3K9itjsE0MsBTmbqwovu6lup1i...

BUG=669108
==========

to

==========
This CL creates an empty MemoryAllocatorDump under URLRequestContext
so AddOwnershipEdge can attribute memory correctly between 
URLRequestContexts. See the following doc for more details on why it
is needed.

https://docs.google.com/document/d/1-dmr_dVgO090Y5_3K9itjsE0MsBTmbqwovu6lup1i...

BUG=669108

Review-Url: https://codereview.chromium.org/2560593002
==========

[commit-bot: I haz the power, 2017-01-04 21:18:58]

Committed patchset #2 (id:60001)

[commit-bot: I haz the power, 2017-01-04 21:21:30]

Description was changed from

==========
This CL creates an empty MemoryAllocatorDump under URLRequestContext
so AddOwnershipEdge can attribute memory correctly between 
URLRequestContexts. See the following doc for more details on why it
is needed.

https://docs.google.com/document/d/1-dmr_dVgO090Y5_3K9itjsE0MsBTmbqwovu6lup1i...

BUG=669108

Review-Url: https://codereview.chromium.org/2560593002
==========

to

==========
This CL creates an empty MemoryAllocatorDump under URLRequestContext
so AddOwnershipEdge can attribute memory correctly between
URLRequestContexts. See the following doc for more details on why it
is needed.

https://docs.google.com/document/d/1-dmr_dVgO090Y5_3K9itjsE0MsBTmbqwovu6lup1i...

BUG=669108

Committed: https://crrev.com/2a2468bdec640adaa6a08f9ca1cfe465e56e7600
Cr-Commit-Position: refs/heads/master@{#441466}
==========

[commit-bot: I haz the power, 2017-01-04 21:21:32]

Patchset 2 (id:??) landed as
https://crrev.com/2a2468bdec640adaa6a08f9ca1cfe465e56e7600
Cr-Commit-Position: refs/heads/master@{#441466}