Refactor backdrop that is currently used in the maximized mode.

components/exo/shell_surface.cc

Index: components/exo/shell_surface.cc
diff --git a/components/exo/shell_surface.cc b/components/exo/shell_surface.cc
index e4fff6f17a71d2ddb9ce98a97105c2dec3b6f52f..e074092e9302c8327fb307c5923d041f13c3005e 100644
--- a/components/exo/shell_surface.cc
+++ b/components/exo/shell_surface.cc
@@ -44,10 +44,6 @@
 #include "ui/wm/core/window_animations.h"
 #include "ui/wm/core/window_util.h"
 
-#if defined(OS_CHROMEOS)
-#include "chromeos/audio/chromeos_sounds.h"
-#endif
-
 namespace exo {
 namespace {
 
@@ -190,41 +186,6 @@ class ShellSurfaceWidget : public views::Widget {
   DISALLOW_COPY_AND_ASSIGN(ShellSurfaceWidget);
 };
 
-class ShadowUnderlayEventHandler : public ui::EventHandler {
- public:
-  ShadowUnderlayEventHandler() {}
-  ~ShadowUnderlayEventHandler() override {}
-
-  // Overridden from ui::EventHandler:
-  void OnEvent(ui::Event* event) override {
-    // If the event is targeted at the underlay, it means the user has made an
-    // interaction that is outside the surface's bounds and we want to capture
-    // it (usually when in spoken feedback mode). Handle the event (to prevent
-    // behind-windows from receiving it) and play an earcon to notify the user.
-    if (event->IsLocatedEvent()) {
-#if defined(OS_CHROMEOS)
-      const ui::EventType kEarconEventTypes[] = {ui::ET_MOUSE_PRESSED,
-                                                 ui::ET_MOUSEWHEEL,
-                                                 ui::ET_TOUCH_PRESSED,
-                                                 ui::ET_POINTER_DOWN,
-                                                 ui::ET_POINTER_WHEEL_CHANGED,
-                                                 ui::ET_GESTURE_BEGIN,
-                                                 ui::ET_SCROLL,
-                                                 ui::ET_SCROLL_FLING_START};
-      bool is_earcon_event_type =
-          std::find(std::begin(kEarconEventTypes), std::end(kEarconEventTypes),
-                    event->type()) != std::end(kEarconEventTypes);
-      if (is_earcon_event_type)
-        WMHelper::GetInstance()->PlayEarcon(chromeos::SOUND_VOLUME_ADJUST);
-#endif
-      event->SetHandled();
-    }
-  }
-
- private:
-  DISALLOW_COPY_AND_ASSIGN(ShadowUnderlayEventHandler);
-};
-
 }  // namespace
 
 // Helper class used to coalesce a number of changes into one "configure"
@@ -373,7 +334,6 @@ ShellSurface::~ShellSurface() {
     surface_->SetSurfaceDelegate(nullptr);
     surface_->RemoveSurfaceObserver(this);
   }
-  WMHelper::GetInstance()->RemoveAccessibilityObserver(this);
 }
 
 void ShellSurface::AcknowledgeConfigure(uint32_t serial) {
@@ -1039,13 +999,6 @@ void ShellSurface::OnWindowActivated(
 }
 
 ////////////////////////////////////////////////////////////////////////////////
-// WMHelper::AccessibilityObserver overrides:
-
-void ShellSurface::OnAccessibilityModeChanged() {
-  UpdateShadow();
-}
-
-////////////////////////////////////////////////////////////////////////////////
 // WMHelper::DisplayConfigurationObserver overrides:
 
 void ShellSurface::OnDisplayConfigurationChanged() {
@@ -1240,9 +1193,6 @@ void ShellSurface::CreateShellSurfaceWidget(ui::WindowShowState show_state) {
         ui::AcceleratorManager::kNormalPriority, this);
   }
 
-  // Receive accessibility changes to update shadow underlay.
-  WMHelper::GetInstance()->AddAccessibilityObserver(this);
-
   // Show widget next time Commit() is called.
   pending_show_widget_ = true;
 }
@@ -1581,15 +1531,17 @@ void ShellSurface::UpdateShadow() {
 
   aura::Window* window = widget_->GetNativeWindow();
 
-  bool underlay_capture_events =
-      WMHelper::GetInstance()->IsSpokenFeedbackEnabled() && widget_->IsActive();
-  bool black_background_enabled =
-      ((widget_->IsFullscreen() || widget_->IsMaximized()) ||
-       underlay_capture_events) &&
-      ash::wm::GetWindowState(window)->allow_set_bounds_direct() &&
-      window->layer()->GetTargetTransform().IsIdentity();
-
-  if (!shadow_enabled_ && !black_background_enabled) {
+  // Enable the black backdrop layer behind the window if the window
+  // is in immersive fullscreen, maximized, yet the window can control
+  // the bounds of the window in fullscreen/maximize mode (thus the
+  // background can be visible).
+  bool enable_backdrop =
+      (widget_->IsFullscreen() || widget_->IsMaximized()) &&
+      ash::wm::GetWindowState(window)->allow_set_bounds_direct();
+  if (window->GetProperty(aura::client::kHasBackdrop) != enable_backdrop)
+    window->SetProperty(aura::client::kHasBackdrop, enable_backdrop);
+
+  if (!shadow_enabled_) {
     wm::SetShadowElevation(window, wm::ShadowElevation::NONE);
     if (shadow_underlay_)
       shadow_underlay_->Hide();
@@ -1638,9 +1590,6 @@ void ShellSurface::UpdateShadow() {
     if (!shadow_underlay_) {
       shadow_underlay_ = base::MakeUnique<aura::Window>(nullptr);
       shadow_underlay_->set_owned_by_parent(false);
-      shadow_underlay_event_handler_ =
-          base::MakeUnique<ShadowUnderlayEventHandler>();
-      shadow_underlay_->SetTargetHandler(shadow_underlay_event_handler_.get());
       DCHECK(!shadow_underlay_->owned_by_parent());
       // Ensure the background area inside the shadow is solid black.
       // Clients that provide translucent contents should not be using
@@ -1660,25 +1609,6 @@ void ShellSurface::UpdateShadow() {
 
     float shadow_underlay_opacity = shadow_background_opacity_;
 
-    // Put the black background layer behind the window if
-    // 1) the window is in immersive fullscreen, maximized or is active with
-    //    spoken feedback enabled.
-    // 2) the window can control the bounds of the window in fullscreen (
-    //    thus the background can be visible).
-    // 3) the window has no transform (the transformed background may
-    //    not cover the entire background, e.g. overview mode).
-    if (black_background_enabled) {
-      if (shadow_underlay_in_surface_) {
-        shadow_underlay_bounds = gfx::Rect(surface_->window()->bounds().size());
-      } else {
-        gfx::Point origin;
-        origin -= window->bounds().origin().OffsetFromOrigin();
-        shadow_bounds.set_origin(origin);
-        shadow_bounds.set_size(window->parent()->bounds().size());
-      }
-      shadow_underlay_opacity = 1.0f;
-    }
-
     if (!shadow_underlay_in_surface_)
       shadow_underlay_bounds = shadow_bounds;