[ozone/wayland]Don't post OnSubmit/OnPresent if the surface is unregistered

When WaylandSurfaceGpu is unregistered, its task_runner is also expected
to be forgotten. There are crashes caused by not finding the
task_runner. This CL adds a check if the task_runner is unregistered and
avoid posting to non-existent task_runners.

Change-Id: I1b7d64a5b469e365d5d87ecc5f2332e74d2faf15
Bug: 1139518
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2502954Reviewed-by: Robert Kroeger <rjkroege@chromium.org>
Commit-Queue: Kramer Ge <fangzhoug@chromium.org>
Cr-Commit-Position: refs/heads/master@{#821845}

ui/ozone/platform/wayland/gpu/wayland_buffer_manager_gpu.cc

@@ -63,9 +63,12 @@ void WaylandBufferManagerGpu::OnSubmission(gfx::AcceleratedWidget widget,
                                            gfx::SwapResult swap_result) {
   base::AutoLock scoped_lock(lock_);
   DCHECK(io_thread_runner_->BelongsToCurrentThread());
-  DCHECK_EQ(commit_thread_runners_.count(widget), 1u);
+  DCHECK_LE(commit_thread_runners_.count(widget), 1u);
   // Return back to the same thread where the commit request came from.
-  commit_thread_runners_.find(widget)->second->PostTask(
+  auto it = commit_thread_runners_.find(widget);
+  if (it == commit_thread_runners_.end())
+    return;
+  it->second->PostTask(
       FROM_HERE,
       base::BindOnce(&WaylandBufferManagerGpu::SubmitSwapResultOnOriginThread,
                      base::Unretained(this), widget, buffer_id, swap_result));
@@ -77,9 +80,12 @@ void WaylandBufferManagerGpu::OnPresentation(
     const gfx::PresentationFeedback& feedback) {
   base::AutoLock scoped_lock(lock_);
   DCHECK(io_thread_runner_->BelongsToCurrentThread());
-  DCHECK_EQ(commit_thread_runners_.count(widget), 1u);
+  DCHECK_LE(commit_thread_runners_.count(widget), 1u);
   // Return back to the same thread where the commit request came from.
-  commit_thread_runners_.find(widget)->second->PostTask(
+  auto it = commit_thread_runners_.find(widget);
+  if (it == commit_thread_runners_.end())
+    return;
+  it->second->PostTask(
       FROM_HERE,
       base::BindOnce(&WaylandBufferManagerGpu::SubmitPresentationOnOriginThread,
                      base::Unretained(this), widget, buffer_id, feedback));