exo: Implement zcr_linux_explicit_synchronization_v1

components/exo/surface.cc

Index: components/exo/surface.cc
diff --git a/components/exo/surface.cc b/components/exo/surface.cc
index 5f22ec6fd64ad5a361039368515743886f0a1530..2d6a996bd8e4387af8e64c0e91b9696d2bf2d41b 100644
--- a/components/exo/surface.cc
+++ b/components/exo/surface.cc
@@ -260,6 +260,15 @@ void Surface::Attach(Buffer* buffer) {
   pending_buffer_.Reset(buffer ? buffer->AsWeakPtr() : base::WeakPtr<Buffer>());
 }
 
+void Surface::FenceAcquire(std::unique_ptr<gfx::GpuFence> fence) {
+  // A better representation would be good here.

[reveman, 2016/10/09 19:03:17]

TRACE_EVENT1(... "fence", !!fence) would be good enough I think

[fooishbar, 2016/10/12 15:41:56]

Done.

+  TRACE_EVENT1("exo", "Surface::FenceAcquire", "fence", fence.get());
+
+  pending_acquire_fence_ = std::move(fence);
+
+  DLOG(WARNING) << "Surface " << GetSurfaceId().ToString() << ": new acquire-fence";

[reveman, 2016/10/09 19:03:17]

Please remove this debug log before landing this change.

[fooishbar, 2016/10/12 15:41:55]

Done.

+}
+
 void Surface::Damage(const gfx::Rect& damage) {
   TRACE_EVENT1("exo", "Surface::Damage", "damage", damage.ToString());
 
@@ -466,6 +475,7 @@ void Surface::CommitSurfaceHierarchy() {
     has_pending_contents_ = false;
 
     current_buffer_ = std::move(pending_buffer_);
+    acquire_fence_ = std::move(pending_acquire_fence_);
 
     UpdateResource(true);
   }
@@ -715,7 +725,8 @@ void Surface::UpdateResource(bool client_usage) {
   if (current_buffer_.buffer()) {
     texture_mailbox_release_callback =
         current_buffer_.buffer()->ProduceTextureMailbox(
-            &texture_mailbox, state_.only_visible_on_secure_output,
+            &texture_mailbox, std::move(acquire_fence_),

[reveman, 2016/10/09 19:03:17]

I think we need to keep the ownership of the acquire fence here in the surface
instance and just pass a raw pointer to ProduceTextureMailbox() in case we need
to produce a new texture mailbox. this can happen in rare circumstances when the
GPU process has crashed. 

[fooishbar, 2016/10/12 15:41:56]

Phew, that was my guess as to what probably made the most sense. OK great, I'll
do that for v2.

+	    state_.only_visible_on_secure_output,
             client_usage);
   }