Bug 1753612 [Linux] Sychronize access to WindowSurfaceProvider r=lsalzman

- Remove WindowSurfaceProvider::CleanupWindowSurface() method.
- Use default WindowSurfaceProvider destructor.
- Use mutex to public WindowSurfaceProvider methods to avoid race of main and render threads.

Differential Revision: https://phabricator.services.mozilla.com/D138699

widget/gtk/WindowSurfaceProvider.cpp

@@ -39,6 +39,7 @@ using namespace mozilla::layers;
 
 WindowSurfaceProvider::WindowSurfaceProvider()
     : mWindowSurface(nullptr),
+      mMutex("WindowSurfaceProvider"),
       mWindowSurfaceValid(false)
 #ifdef MOZ_WAYLAND
       ,
@@ -54,11 +55,6 @@ WindowSurfaceProvider::WindowSurfaceProvider()
 {
 }
 
-WindowSurfaceProvider::~WindowSurfaceProvider() {
-  CleanupResources();
-  CleanupWindowSurface();
-}
-
 #ifdef MOZ_WAYLAND
 void WindowSurfaceProvider::Initialize(RefPtr<nsWindow> aWidget) {
   mWindowSurfaceValid = false;
@@ -77,6 +73,7 @@ void WindowSurfaceProvider::Initialize(Window aWindow, Visual* aVisual,
 #endif
 
 void WindowSurfaceProvider::CleanupResources() {
+  MutexAutoLock lock(mMutex);
   mWindowSurfaceValid = false;
 #ifdef MOZ_WAYLAND
   mWidget = nullptr;
@@ -89,11 +86,6 @@ void WindowSurfaceProvider::CleanupResources() {
 #endif
 }
 
-void WindowSurfaceProvider::CleanupWindowSurface() {
-  mWindowSurface = nullptr;
-  mWindowSurfaceValid = true;
-}
-
 RefPtr<WindowSurface> WindowSurfaceProvider::CreateWindowSurface() {
 #ifdef MOZ_WAYLAND
   if (GdkIsWaylandDisplay()) {
@@ -137,8 +129,11 @@ WindowSurfaceProvider::StartRemoteDrawingInRegion(
     return nullptr;
   }
 
+  MutexAutoLock lock(mMutex);
+
   if (!mWindowSurfaceValid) {
-    CleanupWindowSurface();
+    mWindowSurface = nullptr;
+    mWindowSurfaceValid = true;
   }
 
   if (!mWindowSurface) {
@@ -166,6 +161,7 @@ WindowSurfaceProvider::StartRemoteDrawingInRegion(
 
 void WindowSurfaceProvider::EndRemoteDrawingInRegion(
     gfx::DrawTarget* aDrawTarget, const LayoutDeviceIntRegion& aInvalidRegion) {
+  MutexAutoLock lock(mMutex);
   // Commit to mWindowSurface only when we have a valid one.
   if (mWindowSurface && mWindowSurfaceValid) {
     mWindowSurface->Commit(aInvalidRegion);

widget/gtk/WindowSurfaceProvider.h

@@ -34,7 +34,7 @@ namespace widget {
 class WindowSurfaceProvider final {
  public:
   WindowSurfaceProvider();
-  ~WindowSurfaceProvider();
+  ~WindowSurfaceProvider() = default;
 
   /**
    * Initializes the WindowSurfaceProvider by giving it the window
@@ -67,6 +67,15 @@ class WindowSurfaceProvider final {
   void CleanupWindowSurface();
 
   RefPtr<WindowSurface> mWindowSurface;
+
+  /* While CleanupResources() can be called from Main thread when nsWindow is
+   * destroyed/hidden, StartRemoteDrawingInRegion()/EndRemoteDrawingInRegion()
+   * is called from Compositor thread during rendering.
+   *
+   * As nsWindow CleanupResources() call comes from Gtk/X11 we can't synchronize
+   * that with WebRender so we use lock to synchronize the access.
+   */
+  mozilla::Mutex mMutex;
   // WindowSurface needs to be re-created as underlying window was changed.
   mozilla::Atomic<bool> mWindowSurfaceValid;
 #ifdef MOZ_WAYLAND