Remove the WM_SYSCOMMAND handling from the LegacyRenderWidgetHostHWND class.

Remove the WM_SYSCOMMAND handling from the LegacyRenderWidgetHostHWND class.

This handler was added to forward the message to the parent window for cases where the size of the
parent and the LegacyRenderWidgetHostHWND window were the same.

We can directly call DefWindowProc on the parent window for non client mouse messages which generates
WM_SYSCOMMAND for the parent window.

This simplifies the LegacyRenderWidgetHostHWND class and also fixes bugs with WM_SYSCOMMAND messages not
getting generated correctly due to missing styles on the LegacyRenderWidgetHostHWND hwnd which does not have
the same styles as the parent.

BUG=377367
Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=282248

[ananta, 2014-07-09 02:23:17]

+sky

[cpu_(ooo_6.6-7.5), 2014-07-09 18:00:35]

lgtm

[sky, 2014-07-09 23:06:37]

LGTM

[ananta, 2014-07-09 23:11:33]

The CQ bit was checked by ananta@chromium.org

[commit-bot: I haz the power, 2014-07-09 23:13:55]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/ananta@chromium.org/374283002/1

[commit-bot: I haz the power, 2014-07-10 04:11:50]

Change committed as 282248