Enable pp::flash::FontFile support on Windows

Part 1:
Added Windows implementation using Skia for PepperFlashFontFileHost.
This patch adds a simple Windows implementation of PepperFlashFontFileHost
using Skia to access the font data. By implementing this PepperFlash can
remove some use cases of GDI to support Win32k lockdown.


Part 2:
To support win32k lockdown, Pepper flash needs to switch Win GDI font calls
to pp::flash::FontFile PPAPI. This API was only supported on Linux, and it
is supported on Windows starting from M48.

Considering backward compatibility, we still need to fallback to GDI calls
for Chrome versions where Win32k lockdown is not available yet. We add a new
version of PB_Flash_FontFile interface: PPB_FLASH_FONTFILE_INTERFACE_0_2

This new version does not change any API, its availability shows that
pp::flash:FontFile is supported for Windows, and Pepper flash can use
it to decide whether it should call pp::flash:FontFile API or fall back
to Win GDI calls.


R=bbudge@chromium.org, raymes@chromium.org, forshaw@google.com

Review URL: https://codereview.chromium.org/1416643002

Cr-Commit-Position: refs/heads/master@{#357457}
8 files changed