[GRC] Add Tab-scoped Coordination Unit Graph Observer

services/resource_coordinator/coordination_unit/tab_signal_generator.cc

Index: services/resource_coordinator/coordination_unit/tab_signal_generator.cc
diff --git a/services/resource_coordinator/coordination_unit/tab_signal_generator.cc b/services/resource_coordinator/coordination_unit/tab_signal_generator.cc
new file mode 100644
index 0000000000000000000000000000000000000000..7cc179e6a1b080456fef1bfbd15a42bbd7116db8
--- /dev/null
+++ b/services/resource_coordinator/coordination_unit/tab_signal_generator.cc
@@ -0,0 +1,20 @@
+// 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.
+
+#include "services/resource_coordinator/coordination_unit/tab_signal_generator.h"
+
+#include "services/resource_coordinator/coordination_unit/coordination_unit_impl.h"
+
+namespace resource_coordinator {
+
+TabSignalGenerator::TabSignalGenerator() = default;
+
+TabSignalGenerator::~TabSignalGenerator() = default;
+
+bool TabSignalGenerator::ShouldObserve(
+    const CoordinationUnitImpl* coordination_unit) {
+  return coordination_unit->id().type == CoordinationUnitType::kWebContents;
+}
+
+}  // namespace resource_coordinator