Re-land: Toggle spoken feedback if two fingers are held down.

ash/ash_touch_exploration_manager_chromeos.h

Index: ash/ash_touch_exploration_manager_chromeos.h
diff --git a/ash/ash_touch_exploration_manager_chromeos.h b/ash/ash_touch_exploration_manager_chromeos.h
index 9377059529082610cff0b1f321d6fbc34c85e6bc..8b2aa00018cf3be2902d51482b7a12e68cab54d3 100644
--- a/ash/ash_touch_exploration_manager_chromeos.h
+++ b/ash/ash_touch_exploration_manager_chromeos.h
@@ -10,6 +10,7 @@
 #include "ash/ash_export.h"
 #include "ash/common/system/accessibility_observer.h"
 #include "base/macros.h"
+#include "ui/chromeos/touch_accessibility_enabler.h"
 #include "ui/chromeos/touch_exploration_controller.h"
 #include "ui/display/display_observer.h"
 #include "ui/wm/public/activation_change_observer.h"
@@ -28,6 +29,7 @@ class RootWindowController;
 class ASH_EXPORT AshTouchExplorationManager
     : public AccessibilityObserver,
       public ui::TouchExplorationControllerDelegate,
+      public ui::TouchAccessibilityEnablerDelegate,
       public display::DisplayObserver,
       public aura::client::ActivationChangeObserver {
  public:
@@ -52,6 +54,10 @@ class ASH_EXPORT AshTouchExplorationManager
   void OnDisplayMetricsChanged(const display::Display& display,
                                uint32_t changed_metrics) override;
 
+  // TouchAccessibilityEnablerDelegate overrides:
+  void PlaySpokenFeedbackToggleCountdown(int tick_count) override;
+  void ToggleSpokenFeedback() override;
+
   // aura::client::ActivationChangeObserver overrides:
   void OnWindowActivated(
       aura::client::ActivationChangeObserver::ActivationReason reason,
@@ -67,6 +73,7 @@ class ASH_EXPORT AshTouchExplorationManager
   bool VolumeAdjustSoundEnabled();
 
   std::unique_ptr<ui::TouchExplorationController> touch_exploration_controller_;
+  std::unique_ptr<ui::TouchAccessibilityEnabler> touch_accessibility_enabler_;
   RootWindowController* root_window_controller_;
   chromeos::CrasAudioHandler* audio_handler_;