exo: Implement zcr_linux_explicit_synchronization_v1

components/exo/display.h

Index: components/exo/display.h
diff --git a/components/exo/display.h b/components/exo/display.h
index d4f3b3d08065b522f902612fe7fabe6c23a806de..bb778db32057ad0393d28d847de59aa10b2675f7 100644
--- a/components/exo/display.h
+++ b/components/exo/display.h
@@ -21,6 +21,7 @@
 #endif
 
 namespace gfx {
+class GpuFence;
 class Point;
 }
 
@@ -61,6 +62,9 @@ class Display {
       gfx::BufferFormat format,
       const std::vector<gfx::NativePixmapPlane>& planes,
       std::vector<base::ScopedFD>&& fds);
+
+  // Creates a GpuFence for a Linux fence file descriptor.
+  std::unique_ptr<gfx::GpuFence> CreateLinuxFence(base::ScopedFD fd);
 #endif
 
   // Creates a shell surface for an existing surface.