ozone/wayland: Make surface ownership transferrable

This is required to be able to transfer WaylandWindow's surface
ownership over to WindowDragController in case it gets destroyed in the
middle of a window/tab dragging DnD session. Refer to [1] and [2] for
more details.

Bug: 896640

[1] https://chromium-review.googlesource.com/c/chromium/src/+/2267637
[2] https://docs.google.com/document/d/1s6OwTi_WC-pS21WLGQYI39yw2m42ZlVolUXBclljXB4/edit?usp=sharing

R=msisov@igalia.com

Change-Id: I69360ab208e8754625b5fcd37614530589f0d5c4
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2267618
Commit-Queue: Nick Yamane <nickdiego@igalia.com>
Reviewed-by: Maksim Sisov <msisov@igalia.com>
Cr-Commit-Position: refs/heads/master@{#782992}

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

@@ -4,11 +4,15 @@
 
 #include "ui/ozone/platform/wayland/host/wayland_surface.h"
 
+#include "ui/ozone/platform/wayland/host/wayland_connection.h"
 #include "ui/ozone/platform/wayland/host/wayland_window.h"
 
 namespace ui {
 
-WaylandSurface::WaylandSurface() = default;
+WaylandSurface::WaylandSurface(WaylandConnection* connection,
+                               WaylandWindow* root_window)
+    : root_window_(root_window), surface_(connection->CreateSurface()) {}
+
 WaylandSurface::~WaylandSurface() = default;
 
 gfx::AcceleratedWidget WaylandSurface::GetWidget() const {

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

@@ -5,17 +5,20 @@
 #ifndef UI_OZONE_PLATFORM_WAYLAND_HOST_WAYLAND_SURFACE_H_
 #define UI_OZONE_PLATFORM_WAYLAND_HOST_WAYLAND_SURFACE_H_
 
+#include <cstdint>
+
 #include "ui/gfx/native_widget_types.h"
 #include "ui/ozone/platform/wayland/common/wayland_object.h"
 
 namespace ui {
 
+class WaylandConnection;
 class WaylandWindow;
 
 // Wrapper of a wl_surface, owned by a WaylandWindow or a WlSubsurface.
 class WaylandSurface {
  public:
-  WaylandSurface();
+  WaylandSurface(WaylandConnection* connection, WaylandWindow* root_window);
   WaylandSurface(const WaylandSurface&) = delete;
   WaylandSurface& operator=(const WaylandSurface&) = delete;
   ~WaylandSurface();
@@ -23,6 +26,7 @@ class WaylandSurface {
   WaylandWindow* root_window() const { return root_window_; }
   wl_surface* surface() const { return surface_.get(); }
   int32_t buffer_scale() const { return buffer_scale_; }
+  void set_buffer_scale(int32_t scale) { buffer_scale_ = scale; }
 
   // gfx::AcceleratedWidget identifies a wl_surface or a ui::WaylandWindow. Note
   // that GetWidget() and GetRootWidget() do not necessarily return the same
@@ -33,10 +37,10 @@ class WaylandSurface {
  private:
   WaylandWindow* root_window_ = nullptr;
   wl::Object<wl_surface> surface_;
+
   // Wayland's scale factor for the output that this window currently belongs
   // to.
   int32_t buffer_scale_ = 1;
-  friend class WaylandWindow;
 };
 
 }  // namespace ui

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

@@ -80,7 +80,8 @@ void WaylandWindow::UpdateBufferScale(bool update_bounds) {
 }
 
 gfx::AcceleratedWidget WaylandWindow::GetWidget() const {
-  return wayland_surface_.GetWidget();
+  DCHECK(wayland_surface_);
+  return wayland_surface_->GetWidget();
 }
 void WaylandWindow::SetPointerFocus(bool focus) {
   has_pointer_focus_ = focus;
@@ -316,6 +317,12 @@ void WaylandWindow::SetBoundsDip(const gfx::Rect& bounds_dip) {
 }
 
 bool WaylandWindow::Initialize(PlatformWindowInitProperties properties) {
+  wayland_surface_ = std::make_unique<WaylandSurface>(connection_, this);
+  if (!surface()) {
+    LOG(ERROR) << "Failed to create wl_surface";
+    return false;
+  }
+
   // Properties contain DIP bounds but the buffer scale is initially 1 so it's
   // OK to assign.  The bounds will be recalculated when the buffer scale
   // changes.
@@ -324,12 +331,6 @@ bool WaylandWindow::Initialize(PlatformWindowInitProperties properties) {
   opacity_ = properties.opacity;
   type_ = properties.type;
 
-  wayland_surface_.surface_ = connection_->CreateSurface();
-  wayland_surface_.root_window_ = this;
-  if (!surface()) {
-    LOG(ERROR) << "Failed to create wl_surface";
-    return false;
-  }
   wl_surface_set_user_data(surface(), this);
   AddSurfaceListener();
 
@@ -352,12 +353,13 @@ bool WaylandWindow::Initialize(PlatformWindowInitProperties properties) {
 
 void WaylandWindow::SetBufferScale(int32_t new_scale, bool update_bounds) {
   DCHECK_GT(new_scale, 0);
+  DCHECK(wayland_surface_);
 
   if (new_scale == buffer_scale())
     return;
 
   auto old_scale = buffer_scale();
-  wayland_surface_.buffer_scale_ = new_scale;
+  wayland_surface_->set_buffer_scale(new_scale);
   if (update_bounds)
     SetBoundsDip(gfx::ScaleToRoundedRect(bounds_px_, 1.0 / old_scale));
 

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

@@ -54,8 +54,8 @@ class WaylandWindow : public PlatformWindow, public PlatformEventDispatcher {
   // to do so (this is not needed upon window initialization).
   void UpdateBufferScale(bool update_bounds);
 
-  WaylandSurface* wayland_surface() { return &wayland_surface_; }
-  wl_surface* surface() const { return wayland_surface_.surface(); }
+  WaylandSurface* wayland_surface() { return wayland_surface_.get(); }
+  wl_surface* surface() const { return wayland_surface_->surface(); }
 
   void set_parent_window(WaylandWindow* parent_window) {
     parent_window_ = parent_window;
@@ -82,7 +82,7 @@ class WaylandWindow : public PlatformWindow, public PlatformEventDispatcher {
   void set_child_window(WaylandWindow* window) { child_window_ = window; }
   WaylandWindow* child_window() const { return child_window_; }
 
-  int32_t buffer_scale() const { return wayland_surface_.buffer_scale(); }
+  int32_t buffer_scale() const { return wayland_surface_->buffer_scale(); }
   int32_t ui_scale() const { return ui_scale_; }
 
   const base::flat_set<uint32_t>& entered_outputs_ids() const {
@@ -216,7 +216,7 @@ class WaylandWindow : public PlatformWindow, public PlatformEventDispatcher {
   WaylandWindow* parent_window_ = nullptr;
   WaylandWindow* child_window_ = nullptr;
 
-  WaylandSurface wayland_surface_;
+  std::unique_ptr<WaylandSurface> wayland_surface_;
 
   // The current cursor bitmap (immutable).
   scoped_refptr<BitmapCursorOzone> bitmap_;