Added MemoryMonitor for Linux (with test)

components/memory_coordinator/browser/memory_monitor_linux.h

Index: components/memory_coordinator/browser/memory_monitor_linux.h
diff --git a/components/memory_coordinator/browser/memory_monitor_linux.h b/components/memory_coordinator/browser/memory_monitor_linux.h
new file mode 100644
index 0000000000000000000000000000000000000000..eda27791835cc02aa48c8914ef5fc2058b79bf29
--- /dev/null
+++ b/components/memory_coordinator/browser/memory_monitor_linux.h
@@ -0,0 +1,38 @@
+// Copyright (c) 2016 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 COMPONENTS_MEMORY_COORDINATOR_BROWSER_MEMORY_MONITOR_LINUX_H_
+#define COMPONENTS_MEMORY_COORDINATOR_BROWSER_MEMORY_MONITOR_LINUX_H_
+
+#include "components/memory_coordinator/browser/memory_monitor.h"
+#include "components/memory_coordinator/common/memory_coordinator_export.h"
+
+namespace base {
+struct SystemMemoryInfoKB;
+}  // namespace base
+
+namespace memory_coordinator {
+
+// A memory monitor for the Linux platform.
+class MEMORY_COORDINATOR_EXPORT MemoryMonitorLinux : public MemoryMonitor {
+ public:
+  MemoryMonitorLinux(MemoryMonitorDelegate* delegate);
+  ~MemoryMonitorLinux() override {}
+
+  // MemoryMonitor:
+  int GetFreeMemoryUntilCriticalMB() override;
+
+  // Factory function to create an instance of this class.
+  static std::unique_ptr<MemoryMonitorLinux> Create(
+      MemoryMonitorDelegate* delegate);
+
+ private:
+  // The delegate to be used for retrieving system memory information. Used as a
+  // testing seam.
+  MemoryMonitorDelegate* delegate_;
+};
+
+}  // namespace memory_coordinator
+
+#endif  // COMPONENTS_MEMORY_COORDINATOR_BROWSER_MEMORY_MONITOR_LINUX_H_