Provide renderers with memory pressure signals.

content/public/browser/memory_pressure_controller.h

Index: content/public/browser/memory_pressure_controller.h
diff --git a/content/public/browser/memory_pressure_controller.h b/content/public/browser/memory_pressure_controller.h
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+// Copyright 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 CONTENT_PUBLIC_BROWSER_MEMORY_PRESSURE_CONTROLLER_H_
+#define CONTENT_PUBLIC_BROWSER_MEMORY_PRESSURE_CONTROLLER_H_
+
+#include "base/memory/memory_pressure_listener.h"
+#include "content/common/content_export.h"
+
+namespace content {
+
+class BrowserChildProcessHost;
+class RenderProcessHost;
+
+// Allows content embedders to forward memory pressure events from the main
+// browser process to children processes. For more details see
+// content/browser/memory/memory_pressure_controller_impl.h.
+class CONTENT_EXPORT MemoryPressureController {
+ public:
+
+  // Sends a memory pressure notification to the specified browser child process
+  // via its attached MemoryMessageFilter. May be called on any thread.
+  static void SendPressureNotification(
+      const BrowserChildProcessHost* child_process_host,
+      base::MemoryPressureListener::MemoryPressureLevel level);
+
+  // Sends a memory pressure notification to the specified renderer process via
+  // its attached MemoryMessageFilter. May be called on any thread.
+  static void SendPressureNotification(
+      const RenderProcessHost* render_process_host,
+      base::MemoryPressureListener::MemoryPressureLevel level);
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(MemoryPressureController);
+};
+
+}  // namespace content
+
+#endif  // CONTENT_PUBLIC_BROWSER_MEMORY_PRESSURE_CONTROLLER_H_