aura: Use PlatformWindow from WindowTreeHost.

ui/aura/aura.gyp

Index: ui/aura/aura.gyp
diff --git a/ui/aura/aura.gyp b/ui/aura/aura.gyp
index 33ef09556b3fc5b4c216ae06bb878566829e74f6..6a5788feed05f09a85edc5621d0ef00bba52b702 100644
--- a/ui/aura/aura.gyp
+++ b/ui/aura/aura.gyp
@@ -124,6 +124,7 @@
         ['OS=="win"', {
           'dependencies': [
             '../metro_viewer/metro_viewer.gyp:metro_viewer_messages',
+            '../platform_window/win/win_window.gyp:win_window',

[Ben Goodger (Google), 2014/07/21 17:39:50]

quick note... any reason you didn't provide a single gyp file for
platform_window? you've done all this work to provide a cross platform
encapsulation for a window but then when you use it you have to include
platform-specific gyp files...

[sadrul, 2014/07/22 20:43:29]

It is necessary to have at least a separate x11_window target so that it can be
used from ozone. So I changed this to have a platform_window_base target,
x11_window and win_window to be on top of that, and another platform_window
target that depends on platform_window_base and win_window/x11_window. But the
debug build seems unable to build the platform_window target (see patchset#7,
failure log:
http://build.chromium.org/p/tryserver.chromium/builders/win_chromium_compile_...).

[sadrul, 2014/07/23 02:19:15]

I was unable to figure out the build issues :(

I am going to take a look at this again (filed http://crbug.com/396406 to track
the work), but for now, I have reverted this change, and plan on landing it as
is.

             '../../ipc/ipc.gyp:ipc',
           ],
           'sources!': [