gpu: Use ANDROID_native_fence_sync instead of ARM_implicit_external_sync.

gpu/command_buffer/common/capabilities.h

Index: gpu/command_buffer/common/capabilities.h
diff --git a/gpu/command_buffer/common/capabilities.h b/gpu/command_buffer/common/capabilities.h
index 7950779e95261707c9bb5060cf94c03a986437c8..ab7a07782173c85d28d37e00933f22f9992e9fa3 100644
--- a/gpu/command_buffer/common/capabilities.h
+++ b/gpu/command_buffer/common/capabilities.h
@@ -174,9 +174,6 @@ struct GPU_EXPORT Capabilities {
   // See https://crbug.com/710029.
   bool software_to_accelerated_canvas_upgrade = true;
 
-  // When true, non-empty post sub buffer calls are unsupported.
-  bool disable_non_empty_post_sub_buffers = false;
-
   int major_version = 2;
   int minor_version = 0;
 };