[GRC] Add Tab-scoped Coordination Unit Graph Observer

services/resource_coordinator/coordination_unit/tab_signal_generator.h

Index: services/resource_coordinator/coordination_unit/tab_signal_generator.h
diff --git a/services/resource_coordinator/coordination_unit/tab_signal_generator.h b/services/resource_coordinator/coordination_unit/tab_signal_generator.h
new file mode 100644
index 0000000000000000000000000000000000000000..5c5980d7f428d23283aa7162b8a21c56093881c7
--- /dev/null
+++ b/services/resource_coordinator/coordination_unit/tab_signal_generator.h
@@ -0,0 +1,32 @@
+// 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.
+
+#ifndef SERVICES_RESOURCE_COORDINATOR_COORDINATION_UNIT_TAB_SIGNAL_GENERATOR_H_
+#define SERVICES_RESOURCE_COORDINATOR_COORDINATION_UNIT_TAB_SIGNAL_GENERATOR_H_
+
+#include "base/macros.h"
+#include "services/resource_coordinator/coordination_unit/coordination_unit_graph_observer.h"
+
+namespace resource_coordinator {
+
+class CoordinationUnitImpl;
+
+// The TabSignalGenerator is a unified |CoordinationUnitGraphObserver| for
+// calculating and emitting tab-scoped signals. Nonetheless, the observer
+// has access to the whole coordination unit graph and thus can utilize
+// the information contained within the entire graph to generate the signals.
+class TabSignalGenerator : public CoordinationUnitGraphObserver {
+ public:
+  TabSignalGenerator();
+  ~TabSignalGenerator() override;
+
+  bool ShouldObserve(const CoordinationUnitImpl* coordination_unit) override;
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(TabSignalGenerator);
+};
+
+}  // namespace resource_coordinator
+
+#endif  // SERVICES_RESOURCE_COORDINATOR_COORDINATION_UNIT_TAB_SIGNAL_GENERATOR_H_