Load Vulkan layer via settings regardless of GLES layer support (#3713)

The logic to decide how to load the Vulkan interception layer was
based on GLES layer support. This change separates the two APIs, such
that the system settings are use to load the Vulkan interception layer
as soon as the Android version allows it, regardless of GLES layer
support.

Bug: b/147723153#comment61

core/os/android/layers.go

@@ -24,14 +24,9 @@ import (
 
 const eglLayersExt = "EGL_ANDROID_GLES_layers"
 
-// SupportsLayersViaSystemSettings returns whether the given device supports
-// loading GLES and Vulkan layers via the system settings.
-func SupportsLayersViaSystemSettings(d Device) bool {
-	// TODO: this currently looks for the EGL extension that advertises the
-	// GLES layer loading capability. Technically, the extension could be
-	// absent, but the device could still support loading Vulkan layers via
-	// the settings. There doesn't appear to be a way to detect Vulkan support
-	// and we currently assume a device either supports both, or none.
+// SupportsGLESLayersViaSystemSettings returns whether the given device supports
+// loading GLES layers via the system settings.
+func SupportsGLESLayersViaSystemSettings(d Device) bool {
 	exts := d.Instance().GetConfiguration().GetDrivers().GetOpengl().GetExtensions()
 	for _, ext := range exts {
 		if ext == eglLayersExt {
@@ -41,6 +36,14 @@ func SupportsLayersViaSystemSettings(d Device) bool {
 	return false
 }
 
+// SupportsVulkanLayersViaSystemSettings returns whether the given device supports
+// loading Vulkan layers via the system settings.
+func SupportsVulkanLayersViaSystemSettings(d Device) bool {
+	// Supported since Android P / API level 28
+	apiVersion := d.Instance().GetConfiguration().GetOS().GetAPIVersion()
+	return apiVersion >= 28
+}
+
 // SetupLayer initializes d to use either a Vulkan or GLES layer from layerPkgs
 // limited to the app with package appPkg using the system settings and returns
 // a cleanup to remove the layer settings.

gapii/client/adb.go

@@ -111,7 +111,12 @@ func Start(ctx context.Context, p *android.InstalledPackage, a *android.Activity
 	})
 
 	isVulkan := o.APIs&VulkanAPI != uint32(0)
-	useLayers := android.SupportsLayersViaSystemSettings(d)
+	var useLayers bool
+	if isVulkan {
+		useLayers = android.SupportsVulkanLayersViaSystemSettings(d)
+	} else {
+		useLayers = android.SupportsGLESLayersViaSystemSettings(d)
+	}
 
 	if useLayers {
 		log.I(ctx, "Setting up Layer")