Ozone: Avoid blocking in Swapbuffer Call.

ui/gl/gl_surface_ozone.cc

Index: ui/gl/gl_surface_ozone.cc
diff --git a/ui/gl/gl_surface_ozone.cc b/ui/gl/gl_surface_ozone.cc
index 67ab131b7a8c261905ca7fe5bc0a5aef855e2adb..2233ab70f205f892d8f0f827792cadf45a72252a 100644
--- a/ui/gl/gl_surface_ozone.cc
+++ b/ui/gl/gl_surface_ozone.cc
@@ -121,9 +121,11 @@ class GL_EXPORT GLSurfaceOzoneSurfaceless : public SurfacelessEGL {
 
     return SurfacelessEGL::Resize(size);
   }
-  virtual bool SwapBuffers() override {
+  virtual bool SwapBuffersAsync(
+      const SwapCompletionCallback& callback) override {
     // TODO: this should be replaced by a fence when supported by the driver.
     glFlush();
+    ozone_surface_->SetPageFlipCompletionCallback(callback);
     return ozone_surface_->OnSwapBuffers();
   }
   virtual bool ScheduleOverlayPlane(int z_order,
@@ -139,9 +141,11 @@ class GL_EXPORT GLSurfaceOzoneSurfaceless : public SurfacelessEGL {
     return vsync_provider_.get();
   }
   virtual bool SupportsPostSubBuffer() override { return true; }
-  virtual bool PostSubBuffer(int x, int y, int width, int height) override {
+  virtual bool PostSubBufferAsync(
+      int x, int y, int width, int height,
+          const SwapCompletionCallback& callback) override {
     // The actual sub buffer handling is handled at higher layers.
-    SwapBuffers();
+    SwapBuffersAsync(callback);
     return true;
   }