Remove the simplified-fullscreen-ui flag on Mac.

Now the flag is permanently enabled (which it already was by default).
Required so we can start removing the Cocoa code and we don't want to
have to add Mac-specific support for the non-simplified version on
Views.

BUG=610900

Review-Url: https://codereview.chromium.org/2012763005
Cr-Commit-Position: refs/heads/master@{#396355}
diff --git a/chrome/browser/about_flags.cc b/chrome/browser/about_flags.cc
index a0da3c1..30e179c 100644
--- a/chrome/browser/about_flags.cc
+++ b/chrome/browser/about_flags.cc
@@ -1608,7 +1608,8 @@
      ENABLE_DISABLE_VALUE_TYPE(switches::kEnableClearBrowsingDataCounters,
                                switches::kDisableClearBrowsingDataCounters)},
     {"simplified-fullscreen-ui", IDS_FLAGS_SIMPLIFIED_FULLSCREEN_UI_NAME,
-     IDS_FLAGS_SIMPLIFIED_FULLSCREEN_UI_DESCRIPTION, kOsAll,
+     IDS_FLAGS_SIMPLIFIED_FULLSCREEN_UI_DESCRIPTION,
+     kOsWin | kOsLinux | kOsCrOS | kOsAndroid,
      FEATURE_VALUE_TYPE(features::kSimplifiedFullscreenUI)},
     {"experimental-keyboard-lock-ui",
      IDS_FLAGS_EXPERIMENTAL_KEYBOARD_LOCK_UI_NAME,