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

ash/ash_touch_exploration_manager_chromeos.cc

Index: ash/ash_touch_exploration_manager_chromeos.cc
diff --git a/ash/ash_touch_exploration_manager_chromeos.cc b/ash/ash_touch_exploration_manager_chromeos.cc
index 3438d27524c2edaa9165370bfd5c9b082ea12e89..c5bf8dd6e656e936caf5d50ff76f13cb3b493a9a 100644
--- a/ash/ash_touch_exploration_manager_chromeos.cc
+++ b/ash/ash_touch_exploration_manager_chromeos.cc
@@ -102,6 +102,19 @@ void AshTouchExplorationManager::OnDisplayMetricsChanged(
     UpdateTouchExplorationState();
 }
 
+void AshTouchExplorationManager::PlaySpokenFeedbackToggleCountdown(
+    int tick_count) {
+  AccessibilityDelegate* delegate = WmShell::Get()->accessibility_delegate();
+  if (delegate->ShouldToggleSpokenFeedbackViaTouch())
+    delegate->PlaySpokenFeedbackToggleCountdown(tick_count);
+}
+
+void AshTouchExplorationManager::ToggleSpokenFeedback() {
+  AccessibilityDelegate* delegate = WmShell::Get()->accessibility_delegate();
+  if (delegate->ShouldToggleSpokenFeedbackViaTouch())
+    delegate->ToggleSpokenFeedback(ash::A11Y_NOTIFICATION_SHOW);
+}
+
 void AshTouchExplorationManager::OnWindowActivated(
     aura::client::ActivationChangeObserver::ActivationReason reason,
     aura::Window* gained_active,
@@ -129,11 +142,18 @@ void AshTouchExplorationManager::UpdateTouchExplorationState() {
   const bool spoken_feedback_enabled =
       WmShell::Get()->accessibility_delegate()->IsSpokenFeedbackEnabled();
 
+  if (!touch_accessibility_enabler_) {
+    // Always enable gesture to toggle spoken feedback.
+    touch_accessibility_enabler_.reset(new ui::TouchAccessibilityEnabler(
+        root_window_controller_->GetRootWindow(), this));
+  }
+
   if (spoken_feedback_enabled) {
     if (!touch_exploration_controller_.get()) {
       touch_exploration_controller_ =
           base::MakeUnique<ui::TouchExplorationController>(
-              root_window_controller_->GetRootWindow(), this);
+              root_window_controller_->GetRootWindow(), this,
+              touch_accessibility_enabler_.get());
     }
     if (pass_through_surface) {
       const gfx::Rect& work_area =