Draw underlay behind android apps using talkback

components/exo/shell_surface.h

Index: components/exo/shell_surface.h
diff --git a/components/exo/shell_surface.h b/components/exo/shell_surface.h
index 2d445c592c85dcdebe93f96eacf862b2f151b460..54a5081659e42fe0a08aeb5144751a65fc1ffc01 100644
--- a/components/exo/shell_surface.h
+++ b/components/exo/shell_surface.h
@@ -9,6 +9,7 @@
 #include <memory>
 #include <string>
 
+#include "ash/common/system/accessibility_observer.h"
 #include "ash/common/wm/window_state_observer.h"
 #include "base/macros.h"
 #include "base/strings/string16.h"
@@ -42,6 +43,7 @@ class ShellSurface : public SurfaceDelegate,
                      public SurfaceObserver,
                      public views::WidgetDelegate,
                      public views::View,
+                     public ash::AccessibilityObserver,
                      public ash::wm::WindowStateObserver,
                      public aura::WindowObserver,
                      public WMHelper::ActivationObserver {
@@ -194,6 +196,10 @@ class ShellSurface : public SurfaceDelegate,
   // Overridden from views::View:
   gfx::Size GetPreferredSize() const override;
 
+  // Overridden from ash::AccessibilityObserver:
+  void OnAccessibilityModeChanged(
+      ash::AccessibilityNotificationVisibility notify) override;
+
   // Overridden from ash::wm::WindowStateObserver:
   void OnPreWindowStateTypeChange(ash::wm::WindowState* window_state,
                                   ash::wm::WindowStateType old_type) override;
@@ -218,9 +224,7 @@ class ShellSurface : public SurfaceDelegate,
   // Overridden from ui::AcceleratorTarget:
   bool AcceleratorPressed(const ui::Accelerator& accelerator) override;
 
-  const aura::Window* shadow_underlay_for_test() const {
-    return shadow_underlay_;
-  }
+  aura::Window* shadow_underlay() { return shadow_underlay_; }
 
  private:
   class ScopedConfigure;
@@ -291,6 +295,7 @@ class ShellSurface : public SurfaceDelegate,
   int pending_resize_component_ = HTCAPTION;
   aura::Window* shadow_overlay_ = nullptr;
   aura::Window* shadow_underlay_ = nullptr;
+  std::unique_ptr<ui::EventHandler> shadow_underlay_event_handler_;
   gfx::Rect shadow_content_bounds_;
   std::deque<Config> pending_configs_;
   std::unique_ptr<ash::WindowResizer> resizer_;