[linux/wayland] Added some DCHECKs in the output handling. [merge to …

…M102]

This patch adds some diagnostics for a possible issue in output handling
logic.

(cherry picked from commit 5aa732f)

Bug: 1323635
Change-Id: I5fa34348e62a972466b68ac08c1b9b1192fb3b8e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3634462
Commit-Queue: Alexander Dunaev <adunaev@igalia.com>
Reviewed-by: Maksim Sisov <msisov@igalia.com>
Cr-Original-Commit-Position: refs/heads/main@{#1001444}
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3660509
Auto-Submit: Alexander Dunaev <adunaev@igalia.com>
Commit-Queue: Maksim Sisov <msisov@igalia.com>
Cr-Commit-Position: refs/branch-heads/5005@{#982}
Cr-Branched-From: 5b4d945-refs/heads/main@{#992738}

ui/ozone/platform/wayland/host/wayland_surface.cc

@@ -26,6 +26,7 @@
 #include "ui/ozone/platform/wayland/host/wayland_buffer_handle.h"
 #include "ui/ozone/platform/wayland/host/wayland_connection.h"
 #include "ui/ozone/platform/wayland/host/wayland_output.h"
+#include "ui/ozone/platform/wayland/host/wayland_output_manager.h"
 #include "ui/ozone/platform/wayland/host/wayland_subsurface.h"
 #include "ui/ozone/platform/wayland/host/wayland_window.h"
 
@@ -681,10 +682,15 @@ void WaylandSurface::Enter(void* data,
 
   auto* wayland_output =
       static_cast<WaylandOutput*>(wl_output_get_user_data(output));
+
+  DCHECK_NE(surface->connection_->wayland_output_manager()->GetOutput(
+                wayland_output->output_id()),
+            nullptr);
+
   surface->entered_outputs_.emplace_back(wayland_output->output_id());
 
   if (surface->root_window_)
-    surface->root_window_->OnEnteredOutputIdAdded();
+    surface->root_window_->OnEnteredOutput();
 }
 
 // static
@@ -700,27 +706,21 @@ void WaylandSurface::Leave(void* data,
 }
 
 void WaylandSurface::RemoveEnteredOutput(uint32_t output_id) {
-  if (entered_outputs().empty())
-    return;
-
   auto entered_outputs_it_ =
       std::find_if(entered_outputs_.begin(), entered_outputs_.end(),
                    [&output_id](uint32_t id) { return id == output_id; });
+  if (entered_outputs_it_ == entered_outputs_.end())
+    return;
 
-  // The `entered_outputs_` list should be updated,
-  // 1. for wl_surface::leave, when a user switches physical output between two
-  // displays, a surface does not necessarily receive enter events immediately
-  // or until a user resizes/moves it.  This means that switching output between
-  // displays in a single output mode results in leave events, but the surface
-  // might not have received enter event before.  Thus, remove the id of the
-  // output that the surface leaves only if it was stored before.
-  // 2. for wl_registry::global_remove, when wl_output is removed by a server
-  // after the display is unplugged or switched off.
-  if (entered_outputs_it_ != entered_outputs_.end())
-    entered_outputs_.erase(entered_outputs_it_);
+  // In certain use cases, such as switching outputs in the single output
+  // configuration, the compositor may move the surface from one output to
+  // another one, send wl_surface::leave event to it, but defer sending
+  // wl_surface::enter until the user moves or resizes the surface on the new
+  // output.
+  entered_outputs_.erase(entered_outputs_it_);
 
   if (root_window_)
-    root_window_->OnEnteredOutputIdRemoved();
+    root_window_->OnLeftOutput();
 }
 
 void WaylandSurface::SetOverlayPriority(

ui/ozone/platform/wayland/host/wayland_window.cc

@@ -175,6 +175,10 @@ uint32_t WaylandWindow::GetPreferredEnteredOutputId() {
     auto* output_manager = connection_->wayland_output_manager();
     auto* output = output_manager->GetOutput(output_id);
     auto* preferred_output = output_manager->GetOutput(preferred_output_id);
+    // crbug.com/1323635
+    DCHECK(output) << " output " << output_id << " not found!";
+    DCHECK(preferred_output)
+        << " output " << preferred_output_id << " not found!";
     if (output->scale_factor() > preferred_output->scale_factor())
       preferred_output_id = output_id;
   }
@@ -632,7 +636,7 @@ WaylandWindow* WaylandWindow::GetRootParentWindow() {
   return parent_window_ ? parent_window_->GetRootParentWindow() : this;
 }
 
-void WaylandWindow::OnEnteredOutputIdAdded() {
+void WaylandWindow::OnEnteredOutput() {
   // Wayland does weird things for menus so instead of tracking outputs that
   // we entered or left, we take that from the parent window and ignore this
   // event.
@@ -642,7 +646,7 @@ void WaylandWindow::OnEnteredOutputIdAdded() {
   UpdateWindowScale(true);
 }
 
-void WaylandWindow::OnEnteredOutputIdRemoved() {
+void WaylandWindow::OnLeftOutput() {
   // Wayland does weird things for menus so instead of tracking outputs that
   // we entered or left, we take that from the parent window and ignore this
   // event.

ui/ozone/platform/wayland/host/wayland_window.h

@@ -278,12 +278,13 @@ class WaylandWindow : public PlatformWindow,
   WaylandWindow* GetTopMostChildWindow();
 
   // Called by the WaylandSurface attached to this window when that surface
-  // becomes partially or fully within the scanout region of |output|.
-  void OnEnteredOutputIdAdded();
+  // becomes partially or fully within the scanout region of an output that it
+  // wasn't before.
+  void OnEnteredOutput();
 
   // Called by the WaylandSurface attached to this window when that surface
-  // becomes fully outside of the scanout region of |output|.
-  void OnEnteredOutputIdRemoved();
+  // becomes fully outside of one of outputs that it previously resided on.
+  void OnLeftOutput();
 
   // Returns true iff this window is opaque.
   bool IsOpaqueWindow() const;