Put Switch Access tray enable behind flag

Because Switch Access (the feature) is behind a flag, this setting
should only show when that flag is enabled.

Bug: 948084
Change-Id: I60f4a8e072be656045e920fb5ee39fec8490e031
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1548363
Auto-Submit: Anastasia Helfinstein <anastasi@google.com>
Reviewed-by: Mitsuru Oshima <oshima@chromium.org>
Commit-Queue: Anastasia Helfinstein <anastasi@google.com>
Cr-Commit-Position: refs/heads/master@{#646603}

ash/system/accessibility/tray_accessibility.cc

@@ -21,7 +21,9 @@
 #include "ash/system/tray/tray_popup_utils.h"
 #include "ash/system/tray/tray_utils.h"
 #include "ash/system/tray/tri_view.h"
+#include "base/command_line.h"
 #include "base/metrics/user_metrics.h"
+#include "ui/accessibility/accessibility_switches.h"
 #include "ui/base/l10n/l10n_util.h"
 #include "ui/gfx/image/image.h"
 #include "ui/views/controls/separator.h"
@@ -102,9 +104,11 @@ void AccessibilityDetailedView::OnAccessibilityStatusChanged() {
   TrayPopupUtils::UpdateCheckMarkVisibility(virtual_keyboard_view_,
                                             virtual_keyboard_enabled_);
 
-  switch_access_enabled_ = controller->switch_access_enabled();
-  TrayPopupUtils::UpdateCheckMarkVisibility(switch_access_view_,
-                                            switch_access_enabled_);
+  if (switch_access_view_) {
+    switch_access_enabled_ = controller->switch_access_enabled();
+    TrayPopupUtils::UpdateCheckMarkVisibility(switch_access_view_,
+                                              switch_access_enabled_);
+  }
 
   large_cursor_enabled_ = controller->large_cursor_enabled();
   TrayPopupUtils::UpdateCheckMarkVisibility(large_cursor_view_,
@@ -198,12 +202,15 @@ void AccessibilityDetailedView::AppendAccessibilityList() {
           IDS_ASH_STATUS_TRAY_ACCESSIBILITY_VIRTUAL_KEYBOARD),
       virtual_keyboard_enabled_);
 
-  switch_access_enabled_ = controller->switch_access_enabled();
-  switch_access_view_ = AddScrollListCheckableItem(
-      kSwitchAccessIcon,
-      l10n_util::GetStringUTF16(
-          IDS_ASH_STATUS_TRAY_ACCESSIBILITY_SWITCH_ACCESS),
-      switch_access_enabled_);
+  if (base::CommandLine::ForCurrentProcess()->HasSwitch(
+          switches::kEnableExperimentalAccessibilitySwitchAccess)) {
+    switch_access_enabled_ = controller->switch_access_enabled();
+    switch_access_view_ = AddScrollListCheckableItem(
+        kSwitchAccessIcon,
+        l10n_util::GetStringUTF16(
+            IDS_ASH_STATUS_TRAY_ACCESSIBILITY_SWITCH_ACCESS),
+        switch_access_enabled_);
+  }
 
   scroll_content()->AddChildView(CreateListSubHeaderSeparator());