Address Win/Clang style plugin error in hwnd_message_handler.h

Address Win/Clang style plugin error in hwnd_message_handler.h

This should fix the error below, and also make the code adhere to the comment
in the header: "The WeakPtrFactories below must occur last" :-)

In file included from ..\..\ui\views\win\hwnd_message_handler.cc:5:
..\..\ui/views/win/hwnd_message_handler.h(594,44) :  error: [chromium-style]
WeakPtrFactory members which refer to their outer class must be the last member
in the outer class definition.
  base::WeakPtrFactory<HWNDMessageHandler> autohide_factory_;
                                           ^

BUG=82385
TBR=sky

Committed: https://crrev.com/49bac10701d666cd09a9a636ed599ece997fe330
Cr-Commit-Position: refs/heads/master@{#343096}

[hans, 2015-08-12 20:30:03]

hans@chromium.org changed reviewers:
+ sky@chromium.org

[hans, 2015-08-12 20:30:03]

Please take a look.

[hans, 2015-08-12 20:30:17]

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

[commit-bot: I haz the power, 2015-08-12 20:30:45]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1286273002/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1286273002/1

[commit-bot: I haz the power, 2015-08-12 21:13:01]

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

[commit-bot: I haz the power, 2015-08-12 21:13:02]

Dry run: This issue passed the CQ dry run.

[hans, 2015-08-12 21:18:17]

tbr'ing to hopefully get the bots green today.

[hans, 2015-08-12 21:18:20]

The CQ bit was checked by hans@chromium.org

[commit-bot: I haz the power, 2015-08-12 21:18:59]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1286273002/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1286273002/1

[commit-bot: I haz the power, 2015-08-12 21:24:11]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-08-12 21:25:05]

Patchset 1 (id:??) landed as
https://crrev.com/49bac10701d666cd09a9a636ed599ece997fe330
Cr-Commit-Position: refs/heads/master@{#343096}

[sky, 2015-08-12 23:41:13]

LGTM