ozone: drm: Re-set cursor when GPU process connects

When the GPU process restarts we need to re-send the cursor bitmap since
all GPU process display state is lost.

It looks like it may have been broken all the way back to d818104f
("[Ozone-Drm] Notify cursor of channel established last"), which fixed a
different issue but also caused the message that was intended to restore
the cursor (in CommitBoundsChange) to not get delivered.

Bug: 908682
Test: kill $(pgrep -f type=gpu-process), cursor restored

Change-Id: Ibacab25807995d9402c46f88a7d51b68fe8dfbfc
Reviewed-on: https://chromium-review.googlesource.com/c/1351903Reviewed-by: Daniel Nicoara <dnicoara@chromium.org>
Commit-Queue: Daniel Nicoara <dnicoara@chromium.org>
Cr-Commit-Position: refs/heads/master@{#611166}

ui/ozone/platform/drm/host/drm_cursor.cc

@@ -49,6 +49,7 @@ void DrmCursor::SetDrmCursorProxy(std::unique_ptr<DrmCursorProxy> proxy) {
   DCHECK(thread_checker_.CalledOnValidThread());
   base::AutoLock lock(lock_);
   proxy_ = std::move(proxy);
+  SendCursorShowLocked();
 }
 
 void DrmCursor::ResetDrmCursorProxy() {

ui/ozone/platform/drm/host/drm_gpu_platform_support_host.cc

@@ -78,9 +78,8 @@ void CursorIPC::Send(IPC::Message* message) {
                            FROM_HERE, base::BindOnce(send_callback_, message)))
     return;
 
-  // Drop disconnected updates. DrmWindowHost will call
-  // CommitBoundsChange() when we connect to initialize the cursor
-  // location.
+  // Drop disconnected updates. The cursor will get set once we connect, via
+  // SetDrmCursorProxy().
   delete message;
 }