Merge 245289 "Relanding this as this caused layout tests failure..."

Merge 245289 "Relanding this as this caused layout tests failure..."

> Relanding this as this caused layout tests failures on Win7 due to the call to ShowScrollBars being incorrectly deleted
> in the HWNDMessageHandler::OnSize for a regular WM_SIZE. Added that call back. The rest of the CL is exactly the same as
> the previous one. TBR'ing sky.
> 
> Don't set the scroll styles (WS_VSCROLL and WS_HSCROLL) for WS_POPUP windows.
> 
> This causes issues with select boxes on Windows 7 where hovering at the end of the window returns the scroll WM_NCHITTEST
> codes. Works fine on Windows 8. In any case we don't want the scrolling styles set on windows other than the main Chrome window
> which is the only window which should be receive mousewheel messages.
> 
> I moved the scroll style setting code from the HWNDMessageHandler::OnCreate function to HWNDMessageHandler::Init function as that
> would prevent the initial WM_SIZE message from hiding the scrollbar. The other change is to hide the scrollbars and readd the
> scroll styles if we are sizing the window, when the sizing completes. Basically when we receive the WM_EXITSIZEMOVE message.
> For normal sizing operations we continue to do this in WM_SIZE as before.
> 
> From testing on my thinkpad with Win7, desktop with Win7 and Win8 this works well
> 
> BUG=334454, 334541
> TBR=sky
> 
> Review URL: https://codereview.chromium.org/133273020

TBR=ananta@chromium.org

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=246169

[ananta, 2014-01-21 23:54:02]

Committed patchset #1 manually as r246169.