Revert 85666 - Consolidate ShouldUseNativeFrame/AlwaysUseNativeFrame/UseNativeFrame spaghetti.

Revert 85666 - Consolidate ShouldUseNativeFrame/AlwaysUseNativeFrame/UseNativeFrame spaghetti.

Now there is:

... window::ShouldUseNativeFrame()

Which is basically just a pass-thru to

WindowWin::ShouldUseNativeFrame()

... which can be overridden by subclasses. Native-Frame is a windows-only concept but keeping the API on Window means I don't have to update a lot of call sites.

Window also gains a FrameType state member that toggles three states - default, force-native and force-custom.
This supercedes the "AlwaysUseNativeFrame/AlwaysUseCustomFrame" methods on NonClientView.

I have also hooked up a context menu item behind a command line flag --debug-enable-frame-toggle that allows the frame type for an individual window to be toggled, useful for debugging.

BUG=none
TEST=none
Review URL: http://codereview.chromium.org/7036014

TBR=ben@chromium.org
Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=85702