Very basic change to add a TriggerManager class owned by SafeBrowsingService.

components/safe_browsing/triggers/BUILD.gn

Index: components/safe_browsing/triggers/BUILD.gn
diff --git a/components/safe_browsing/triggers/BUILD.gn b/components/safe_browsing/triggers/BUILD.gn
new file mode 100644
index 0000000000000000000000000000000000000000..9c8901784ab8afa43e45b2087f6b92c1aae1b23c
--- /dev/null
+++ b/components/safe_browsing/triggers/BUILD.gn
@@ -0,0 +1,18 @@
+# Copyright 2017 The Chromium Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+import("//build/config/features.gni")
+
+source_set("triggers") {
+  if (safe_browsing_mode != 0) {
+    sources = [
+      "trigger_manager.cc",
+      "trigger_manager.h",
+    ]
+
+    deps = [
+      "//base:base",
+    ]
+  }
+}