Too many switches namespaces (jumbo win compile fix)

The existance of both a top level ::switches and sub namespace
switches bite again. Inside accessibility code if you just
say "switches" you will resolve to accessibility::switches
if the compiler knows that namespace exists. In jumbo builds
the compiler knows that so this code broke.

The full fix is to either rename the top level |switches| or all
the sub namespace |switches| and that is a messy change (though it
would bring the code closer to style guide conformance).
Same with the |features| namespace.

The fix here is to make the namespace fully qualified by adding
a :: prefix.

TBR=kbabbitt@microsoft.com,sky@chromium.org

Bug: 928811
Change-Id: Ic593a97c1ef653c9e2df411d84ad0dd9d19c2c89
Reviewed-on: https://chromium-review.googlesource.com/c/1472670
Reviewed-by: Daniel Bratell <bratell@opera.com>
Commit-Queue: Daniel Bratell <bratell@opera.com>
Cr-Commit-Position: refs/heads/master@{#632163}
diff --git a/ui/views/accessibility/view_ax_platform_node_delegate_win.cc b/ui/views/accessibility/view_ax_platform_node_delegate_win.cc
index ab33289..a1e7b940 100644
--- a/ui/views/accessibility/view_ax_platform_node_delegate_win.cc
+++ b/ui/views/accessibility/view_ax_platform_node_delegate_win.cc
@@ -89,7 +89,7 @@
   if (!hwnd)
     return nullptr;
 
-  if (switches::IsExperimentalAccessibilityPlatformUIAEnabled()) {
+  if (::switches::IsExperimentalAccessibilityPlatformUIAEnabled()) {
     ui::AXFragmentRootWin* ax_fragment_root =
         ui::AXFragmentRootWin::GetForAcceleratedWidget(hwnd);
     if (ax_fragment_root)