Chromium side of maxTouchPoints implementation.

content/browser/web_contents/web_contents_impl.cc

Index: content/browser/web_contents/web_contents_impl.cc
diff --git a/content/browser/web_contents/web_contents_impl.cc b/content/browser/web_contents/web_contents_impl.cc
index 7d0e6c7deb7c979c39ec12c6dcb253603b3f75e3..27af16015b871f4a78e10940129586444e0cdd16 100644
--- a/content/browser/web_contents/web_contents_impl.cc
+++ b/content/browser/web_contents/web_contents_impl.cc
@@ -601,6 +601,10 @@ WebPreferences WebContentsImpl::GetWebkitPrefs(RenderViewHost* rvh,
   prefs.device_supports_mouse = false;
 #endif
 
+  prefs.pointer_events_max_touch_points_enabled = prefs.touch_enabled &&

[Rick Byers, 2013/10/10 22:42:40]

I don't think you want to look at touch_enabled here.  If touch isn't enabled,
then the API should return 0 not undefined, right?  At least I assume that's
what IE does.

[Rick Byers, 2013/10/10 22:42:40]

Does this override the status=experimental property in
RuntimeEnabledFeatures.in?  I.e. does this cause the API to be exposed even when
we're not running with --enable-experimental-web-platform-features?  I don't
think we want that - let's get it right as experimental, then launch it to all
users by flipping it to stable in a future CL.

If we're going to land support for all platforms before it goes stable (which I
think we can do), then you can just avoid having a pref for this entirely. 
We'll just flip it to stable once all the platforms that support touch supply
some value and then have no need to disable it in some cases.

+      ui::CanDetectMaxTouchPoints();
+  prefs.pointer_events_max_touch_points = ui::MaxTouchPoints();
+
    prefs.touch_adjustment_enabled =
        !command_line.HasSwitch(switches::kDisableTouchAdjustment);
    prefs.compositor_touch_hit_testing =