Use VulkanBrowserCompositorOS only for Aura.

content/browser/BUILD.gn

Index: content/browser/BUILD.gn
diff --git a/content/browser/BUILD.gn b/content/browser/BUILD.gn
index b98c5f9e592e921ffd5c00517ce645615fdce957..f333a9a0dfc17e4ee16b285268364e2cf15d72f2 100644
--- a/content/browser/BUILD.gn
+++ b/content/browser/BUILD.gn
@@ -460,6 +460,12 @@ source_set("browser") {
         rebase_path(content_browser_gypi_values.compositor_browser_sources,
                     ".",
                     "//content")
+    if (enable_vulkan) {
+      sources += [
+        "compositor/vulkan_browser_compositor_output_surface.cc",
+        "compositor/vulkan_browser_compositor_output_surface.h",
+      ]
+    }
     if (!use_x11) {
       sources -= [
         "compositor/software_output_device_x11.cc",
@@ -478,13 +484,6 @@ source_set("browser") {
     deps += [ "//ui/compositor" ]
   }
 
-  if (enable_vulkan) {
-    sources += [
-      "compositor/vulkan_browser_compositor_output_surface.cc",
-      "compositor/vulkan_browser_compositor_output_surface.h",
-    ]
-  }
-
   if (enable_web_speech) {
     deps += [ "//third_party/flac" ]
   }