scheduler: Always create a real scheduler in unit tests

content/test/BUILD.gn

Index: content/test/BUILD.gn
diff --git a/content/test/BUILD.gn b/content/test/BUILD.gn
index 7a4377a1a6010baaa5e8dc4cb847fd09d5da23c8..848dea1b87bd5c8df96313aa7325a3310af53a5d 100644
--- a/content/test/BUILD.gn
+++ b/content/test/BUILD.gn
@@ -56,6 +56,7 @@ source_set("test_support") {
     public_deps += [ "//third_party/WebKit/public:blink" ]
     deps += [
       "//components/scheduler:scheduler",
+      "//components/scheduler:test_support",
       "//content/browser/speech/proto",
       "//content/public/child",
       "//content/gpu",