[X11] Track window occlusion state

This allows different behavior for tab discarding if a window is fully
obscured by another window.

R=sky

Bug: 1240108
Change-Id: Ifb945639ee6a1150894fb91499ac70e980753029
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3101775
Commit-Queue: Thomas Anderson <thomasanderson@chromium.org>
Reviewed-by: Scott Violet <sky@chromium.org>
Cr-Commit-Position: refs/heads/main@{#914939}

ui/platform_window/x11/x11_window.cc

@@ -1878,6 +1878,20 @@ void X11Window::AfterActivationStateChanged() {
     OnXWindowIsActiveChanged(is_active);
 }
 
+void X11Window::MaybeUpdateOcclusionState() {
+  PlatformWindowOcclusionState occlusion_state =
+      is_occluded_ ? PlatformWindowOcclusionState::kOccluded
+                   : PlatformWindowOcclusionState::kVisible;
+
+  if (!window_mapped_in_client_ || IsMinimized())
+    occlusion_state = PlatformWindowOcclusionState::kHidden;
+
+  if (occlusion_state != occlusion_state_) {
+    occlusion_state_ = occlusion_state;
+    platform_window_delegate_->OnOcclusionStateChanged(occlusion_state);
+  }
+}
+
 void X11Window::OnCrossingEvent(bool enter,
                                 bool focus_in_window_or_ancestor,
                                 x11::NotifyMode mode,
@@ -2096,6 +2110,9 @@ void X11Window::HandleEvent(const x11::Event& xev) {
       OnWorkspaceUpdated();
   } else if (auto* selection = xev.As<x11::SelectionNotifyEvent>()) {
     OnXWindowSelectionEvent(*selection);
+  } else if (auto* visibility = xev.As<x11::VisibilityNotifyEvent>()) {
+    is_occluded_ = visibility->state == x11::Visibility::FullyObscured;
+    MaybeUpdateOcclusionState();
   }
 }
 
@@ -2196,8 +2213,6 @@ void X11Window::OnWMStateUpdated() {
 
 void X11Window::UpdateWindowProperties(
     const base::flat_set<x11::Atom>& new_window_properties) {
-  was_minimized_ = IsMinimized();
-
   window_properties_ = new_window_properties;
 
   // Ignore requests by the window manager to enter or exit fullscreen (e.g. as
@@ -2208,6 +2223,7 @@ void X11Window::UpdateWindowProperties(
   is_always_on_top_ = HasWMSpecProperty(window_properties_,
                                         x11::GetAtom("_NET_WM_STATE_ABOVE"));
   OnXWindowStateChanged();
+  MaybeUpdateOcclusionState();
   ResetWindowRegion();
 }
 

ui/platform_window/x11/x11_window.h

@@ -41,18 +41,17 @@ class LocatedEvent;
 class WorkspaceExtensionDelegate;
 
 // PlatformWindow implementation for X11.
-class X11_WINDOW_EXPORT X11Window
-    : public PlatformWindow,
-      public WmMoveResizeHandler,
-      public PlatformEventDispatcher,
-      public x11::EventObserver,
-      public WorkspaceExtension,
-      public X11Extension,
-      public WmDragHandler,
-      public XDragDropClient::Delegate,
-      public X11MoveLoopDelegate,
-      public WmMoveLoopHandler,
-      public X11DesktopWindowMoveClient::Delegate {
+class X11_WINDOW_EXPORT X11Window : public PlatformWindow,
+                                    public WmMoveResizeHandler,
+                                    public PlatformEventDispatcher,
+                                    public x11::EventObserver,
+                                    public WorkspaceExtension,
+                                    public X11Extension,
+                                    public WmDragHandler,
+                                    public XDragDropClient::Delegate,
+                                    public X11MoveLoopDelegate,
+                                    public WmMoveLoopHandler,
+                                    public X11DesktopWindowMoveClient::Delegate {
  public:
   explicit X11Window(PlatformWindowDelegate* platform_window_delegate);
   ~X11Window() override;
@@ -283,6 +282,8 @@ class X11_WINDOW_EXPORT X11Window
   // Handle the state change since BeforeActivationStateChanged().
   void AfterActivationStateChanged();
 
+  void MaybeUpdateOcclusionState();
+
   void DelayedResize(const gfx::Rect& bounds_in_pixels);
 
   // If mapped, sends a message to the window manager to enable or disable the
@@ -387,6 +388,12 @@ class X11_WINDOW_EXPORT X11Window
   // True if the window should stay on top of most other windows.
   bool is_always_on_top_ = false;
 
+  // True if the window is fully obscured by another window.
+  bool is_occluded_ = false;
+
+  PlatformWindowOcclusionState occlusion_state_ =
+      PlatformWindowOcclusionState::kUnknown;
+
   // Does |xwindow_| have the pointer grab (XI2 or normal)?
   bool has_pointer_grab_ = false;
 
@@ -420,8 +427,6 @@ class X11_WINDOW_EXPORT X11Window
   bool had_pointer_grab_ = false;
   bool had_window_focus_ = false;
 
-  bool was_minimized_ = false;
-
   // Used for synchronizing between |xwindow_| and desktop compositor during
   // resizing.
   x11::Sync::Counter update_counter_{};