Add MemoryCoordinator

components/memory_coordinator/child/BUILD.gn

Index: components/memory_coordinator/child/BUILD.gn
diff --git a/components/memory_coordinator/child/BUILD.gn b/components/memory_coordinator/child/BUILD.gn
index db58c2ddd4dd7b9ae6da16dbc058886815869340..a94071c206097dd1b7bd327aa16129073e1f3405 100644
--- a/components/memory_coordinator/child/BUILD.gn
+++ b/components/memory_coordinator/child/BUILD.gn
@@ -4,6 +4,8 @@
 
 source_set("child") {
   sources = [
+    "blink_memory_coordinator_client.cc",
+    "blink_memory_coordinator_client.h",
     "child_memory_coordinator_impl.cc",
     "child_memory_coordinator_impl.h",
   ]
@@ -12,6 +14,7 @@ source_set("child") {
     "//base",
     "//components/memory_coordinator/common",
     "//components/memory_coordinator/public/interfaces",
+    "//third_party/WebKit/public:blink",
   ]
 }