[Impeller] turned on validations for all debug builds (#45350)

fixes flutter/flutter#133794

This adds the following shared libraries to the flutter.jar for debug builds on arm64:
```
lib/arm64-v8a/libVkLayer_khronos_validation.so
lib/arm64-v8a/libc++_shared.so
```

[C++, Objective-C, Java style guides]: https://github.com/flutter/engine/blob/main/CONTRIBUTING.md#style

DEPS

@@ -261,7 +261,7 @@ allowed_hosts = [
 ]
 
 deps = {
-  'src': 'https://github.com/flutter/buildroot.git' + '@' + '6b0243e97d94836767ea8b94a477d7d15ee3bb91',
+  'src': 'https://github.com/flutter/buildroot.git' + '@' + 'b615dd6af4c2e95a388060151c7fd1e429e34d61',
 
    # Fuchsia compatibility
    #

shell/platform/android/BUILD.gn

@@ -492,12 +492,15 @@ action("android_jar") {
 
   if (enable_vulkan_validation_layers) {
     assert(impeller_enable_vulkan)
-    deps += [ "//third_party/vulkan_validation_layers" ]
+    apilevel26_toolchain = "//build/toolchain/android:clang_arm64_apilevel26"
+    validation_layer_target =
+        "//third_party/vulkan_validation_layers($apilevel26_toolchain)"
+    validation_layer_out_dir =
+        get_label_info(validation_layer_target, "root_out_dir")
+    deps += [ validation_layer_target ]
     args += [
       "--native_lib",
-      rebase_path("libVkLayer_khronos_validation.so",
-                  root_build_dir,
-                  root_build_dir),
+      rebase_path("$validation_layer_out_dir/libVkLayer_khronos_validation.so"),
     ]
     if (current_cpu == "arm64") {
       args += [

shell/platform/android/android_context_vulkan_impeller.cc

@@ -38,7 +38,12 @@ static std::shared_ptr<impeller::Context> CreateImpellerContext(
   settings.cache_directory = fml::paths::GetCachesDirectory();
   settings.enable_validation = enable_vulkan_validation;
 
-  FML_LOG(ERROR) << "Using the Impeller rendering backend (Vulkan).";
+  if (settings.enable_validation) {
+    FML_LOG(ERROR) << "Using the Impeller rendering backend (Vulkan with "
+                      "Validation Layers).";
+  } else {
+    FML_LOG(ERROR) << "Using the Impeller rendering backend (Vulkan).";
+  }
 
   return impeller::ContextVK::Create(std::move(settings));
 }

shell/platform/android/io/flutter/embedding/engine/loader/FlutterLoader.java

@@ -214,6 +214,13 @@ public InitResult call() {
     }
   }
 
+  private static boolean areValidationLayersOnByDefault() {
+    if (BuildConfig.DEBUG && Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
+      return Build.SUPPORTED_ABIS[0].equals("arm64-v8a");
+    }
+    return false;
+  }
+
   /**
    * Blocks until initialization of the native system has completed.
    *
@@ -324,7 +331,8 @@ public void ensureInitializationComplete(
         if (metaData.getBoolean(ENABLE_IMPELLER_META_DATA_KEY, false)) {
           shellArgs.add("--enable-impeller");
         }
-        if (metaData.getBoolean(ENABLE_VULKAN_VALIDATION_META_DATA_KEY, false)) {
+        if (metaData.getBoolean(
+            ENABLE_VULKAN_VALIDATION_META_DATA_KEY, areValidationLayersOnByDefault())) {
           shellArgs.add("--enable-vulkan-validation");
         }
         String backend = metaData.getString(IMPELLER_BACKEND_META_DATA_KEY);

tools/gn

@@ -646,7 +646,9 @@ def to_gn_args(args):
   if args.unoptimized and args.target_os == 'android' and args.android_cpu == 'arm64':
     enable_vulkan_validation = True
 
-  if enable_vulkan_validation:
+  if enable_vulkan_validation or (args.enable_impeller_vulkan and
+                                  runtime_mode == 'debug' and
+                                  gn_args['target_cpu'] == 'arm64'):
     gn_args['enable_vulkan_validation_layers'] = True
     if args.target_os == 'android':
       gn_args['android_api_level'] = 26