Merge 244295 "Ensure that trackpad and trackpoint scrolling work..."

Merge 244295 "Ensure that trackpad and trackpoint scrolling work..."

> Ensure that trackpad and trackpoint scrolling works on Windows desktop Aura with legacy trackpad drivers.
> 
> Legacy trackpad drivers like the older synaptics drivers have bugs where in they don't generate the WM_MOUSEWHEEL
> messages for applications unless there is an entry for the application with the class name of the window in their
> config file. If an entry does not exist here, these drivers expect the window to have the WS_VSCROLL/WS_HSCROLL style
> to generate the legacy WM_VSCROLL/WM_HSCROLL messages.
> 
> This patch adds these styles to top level windows for Windows Aura. To ensure that Windows does not draw these
> scrollbars, we hide them when the window size changes and readd them in a posted task which works correctly in our
> testing.
> 
> Changes in this patch are as below:-
> 1. Add handlers to the HWNDMessageHandler class for the WM_VSCROLL/WM_HSCROLL messages.
> 2. Forward the scroll events to the HWNDMessageHandlerDelegate which then forwards it off to its delegate.
> 3. Miscellaneous fixes in the events code to allow the WM_VSCROLL/WM_HSCROLL messages to go through.
> 
> BUG=320849
> R=cpu@chromium.org, sky@chromium.org, cpu, sky
> 
> Review URL: https://codereview.chromium.org/133053004

TBR=ananta@chromium.org

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=244298

[ananta, 2014-01-11 01:49:33]

Committed patchset #1 manually as r244298.