[Impeller] attempt to get validation errors from CI unittests.

impeller/aiks/BUILD.gn

@@ -116,6 +116,8 @@ template("aiks_unittests_component") {
       "//flutter/impeller/typographer/backends/stb:typographer_stb_backend",
       "//flutter/testing:testing_lib",
       "//flutter/third_party/txt",
+      "//third_party/vulkan_validation_layers",
+      "//third_party/vulkan_validation_layers:vulkan_gen_json_files",
     ]
     if (defined(invoker.public_configs)) {
       public_configs = invoker.public_configs

impeller/playground/playground_impl.cc

@@ -35,6 +35,7 @@ std::unique_ptr<PlaygroundImpl> PlaygroundImpl::Create(
 #endif  // IMPELLER_ENABLE_OPENGLES
 #if IMPELLER_ENABLE_VULKAN
     case PlaygroundBackend::kVulkan:
+      switches.enable_vulkan_validation = true;
       return std::make_unique<PlaygroundImplVK>(switches);
 #endif  // IMPELLER_ENABLE_VULKAN
     default:

impeller/renderer/backend/vulkan/capabilities_vk.cc

@@ -41,7 +41,7 @@ CapabilitiesVK::CapabilitiesVK(bool enable_validations) {
   validations_enabled_ =
       enable_validations && HasLayer("VK_LAYER_KHRONOS_validation");
   if (enable_validations && !validations_enabled_) {
-    FML_LOG(ERROR)
+    FML_LOG(FATAL)
         << "Requested Impeller context creation with validations but the "
            "validation layers could not be found. Expect no Vulkan validation "
            "checks!";

impeller/tools/impeller.gni

@@ -19,10 +19,10 @@ declare_args() {
 
   # Whether the OpenGLES backend is enabled.
   impeller_enable_opengles =
-      (is_linux || is_win || is_android) && target_os != "fuchsia"
+      (is_linux || is_win || is_android || is_mac) && target_os != "fuchsia"
 
   # Whether the Vulkan backend is enabled.
-  impeller_enable_vulkan = (is_linux || is_win || is_android ||
+  impeller_enable_vulkan = (is_linux || is_win || is_android || is_mac ||
                             enable_unittests) && target_os != "fuchsia"
 
   # Whether playgrounds should run with Vulkan.

tools/gn

@@ -788,15 +788,9 @@ def to_gn_args(args):
   if args.enable_impeller_trace_canvas:
     gn_args['impeller_trace_canvas'] = True
 
-  if args.enable_impeller_vulkan:
-    gn_args['impeller_enable_vulkan'] = True
-
   if args.enable_impeller_vulkan_playgrounds:
     gn_args['impeller_enable_vulkan_playgrounds'] = True
 
-  if args.enable_impeller_opengles:
-    gn_args['impeller_enable_opengles'] = True
-
   if args.prebuilt_impellerc is not None:
     gn_args['impeller_use_prebuilt_impellerc'] = args.prebuilt_impellerc
 
@@ -1253,19 +1247,12 @@ def parse_args(args):
 
   parser.add_argument(
       '--enable-impeller-vulkan-playgrounds',
-      default=False,
+      default=True,
       action='store_true',
       help='Enable the Impeller Vulkan Playgrounds. ' +
       'The Impeller Vulkan backend needs to be enabled.'
   )
 
-  parser.add_argument(
-      '--enable-impeller-opengles',
-      default=False,
-      action='store_true',
-      help='Enable the Impeller OpenGL ES backend.'
-  )
-
   parser.add_argument(
       '--prebuilt-impellerc',
       default=None,