Decompose //extensions/browser/BUILD.gn

extensions/browser/api/system_memory/BUILD.gn

Index: extensions/browser/api/system_memory/BUILD.gn
diff --git a/services/file/public/interfaces/BUILD.gn b/extensions/browser/api/system_memory/BUILD.gn
similarity index 52%
copy from services/file/public/interfaces/BUILD.gn
copy to extensions/browser/api/system_memory/BUILD.gn
index 8d8e767a261e71db8140fe1c85842c9f10945681..879bbdf7622768956e60436ecb22437753c4afc9 100644
--- a/services/file/public/interfaces/BUILD.gn
+++ b/extensions/browser/api/system_memory/BUILD.gn
@@ -2,14 +2,15 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
-import("//mojo/public/tools/bindings/mojom.gni")
-
-mojom("interfaces") {
+source_set("system_memory") {
   sources = [
-    "file_system.mojom",
+    "memory_info_provider.cc",
+    "memory_info_provider.h",
+    "system_memory_api.cc",
+    "system_memory_api.h",
   ]
 
   deps = [
-    "//components/filesystem/public/interfaces",
+    "//extensions/common/api",
   ]
 }