Bug 1794284 [Wayland] Handle missing shm interface in WaylandBufferSHM/WindowSurfaceWaylandMultiBuffer r=rmader

Differential Revision: https://phabricator.services.mozilla.com/D158946

widget/gtk/WaylandBuffer.cpp

@@ -103,6 +103,11 @@ static int WaylandAllocateShmMemory(int aSize) {
 /* static */
 RefPtr<WaylandShmPool> WaylandShmPool::Create(
     const RefPtr<nsWaylandDisplay>& aWaylandDisplay, int aSize) {
+  if (!aWaylandDisplay->GetShm()) {
+    NS_WARNING("Missing Wayland shm interface!");
+    return nullptr;
+  }
+
   RefPtr<WaylandShmPool> shmPool = new WaylandShmPool(aSize);
 
   shmPool->mShmPoolFd = WaylandAllocateShmMemory(aSize);
@@ -117,7 +122,6 @@ RefPtr<WaylandShmPool> WaylandShmPool::Create(
     return nullptr;
   }
 
-  MOZ_DIAGNOSTIC_ASSERT(aWaylandDisplay->GetShm(), "Missing Shm!");
   shmPool->mShmPool =
       wl_shm_create_pool(aWaylandDisplay->GetShm(), shmPool->mShmPoolFd, aSize);
   if (!shmPool->mShmPool) {

widget/gtk/WindowSurfaceWaylandMultiBuffer.cpp

@@ -197,6 +197,9 @@ already_AddRefed<DrawTarget> WindowSurfaceWaylandMB::Lock(
       mInProgressBuffer = mFrontBuffer;
     } else {
       mInProgressBuffer = ObtainBufferFromPool(lock, mMozContainerSize);
+      if (!mInProgressBuffer) {
+        return nullptr;
+      }
       if (mFrontBuffer) {
         HandlePartialUpdate(lock, aInvalidRegion);
         ReturnBufferToPool(lock, mFrontBuffer);
@@ -326,7 +329,9 @@ RefPtr<WaylandBufferSHM> WindowSurfaceWaylandMB::ObtainBufferFromPool(
   }
 
   RefPtr<WaylandBufferSHM> buffer = WaylandBufferSHM::Create(aSize);
-  mInUseBuffers.AppendElement(buffer);
+  if (buffer) {
+    mInUseBuffers.AppendElement(buffer);
+  }
 
   return buffer;
 }