exo: Implement zcr_linux_explicit_synchronization_v1

components/exo/surface.h

Index: components/exo/surface.h
diff --git a/components/exo/surface.h b/components/exo/surface.h
index 744587db667507e671e4996c4dfc6d5276691dc9..667915eae65f920cfd11ef0b5bbf7d9b14aef8bb 100644
--- a/components/exo/surface.h
+++ b/components/exo/surface.h
@@ -34,6 +34,7 @@ class SurfaceFactory;
 }
 
 namespace gfx {
+class GpuFence;
 class Path;
 }
 
@@ -107,6 +108,10 @@ class Surface : public ui::ContextFactoryObserver {
   // to one surface at a time.
   void Attach(Buffer* buffer);
 
+  // Provide an acquire-fence for the next surface commit. A buffer must be
+  // attached in the same transaction as applying a fence.
+  void SetAcquireFence(std::unique_ptr<gfx::GpuFence> fence);
+
   // Describe the regions where the pending buffer is different from the
   // current surface contents, and where the surface therefore needs to be
   // repainted.
@@ -328,6 +333,10 @@ class Surface : public ui::ContextFactoryObserver {
   // The buffer that will become the content of surface when Commit() is called.
   BufferAttachment pending_buffer_;
 
+  // The fence which will be used to wait before sourcing from
+  // |pending_buffer_|, on next Commit().
+  std::unique_ptr<gfx::GpuFence> pending_fence_;
+
   cc::SurfaceManager* surface_manager_;
 
   scoped_refptr<SurfaceFactoryOwner> factory_owner_;
@@ -367,6 +376,10 @@ class Surface : public ui::ContextFactoryObserver {
   // The buffer that is currently set as content of surface.
   BufferAttachment current_buffer_;
 
+  // The fence which will be used to wait before sourcing from
+  // |current_buffer_|.
+  std::unique_ptr<gfx::GpuFence> fence_;
+
   // The last resource that was sent to a surface.
   cc::TransferableResource current_resource_;