Implement a runtime headless mode for Linux

headless/lib/browser/headless_platform_event_source.h

Index: headless/lib/browser/headless_platform_event_source.h
diff --git a/headless/lib/browser/headless_platform_event_source.h b/headless/lib/browser/headless_platform_event_source.h
new file mode 100644
index 0000000000000000000000000000000000000000..ccd74632567f641729d0c5c37600e00fdb6cdf4d
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+++ b/headless/lib/browser/headless_platform_event_source.h
@@ -0,0 +1,26 @@
+// 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 HEADLESS_LIB_BROWSER_HEADLESS_PLATFORM_EVENT_SOURCE_H_
+#define HEADLESS_LIB_BROWSER_HEADLESS_PLATFORM_EVENT_SOURCE_H_
+
+#include "base/macros.h"
+#include "ui/events/platform/platform_event_source.h"
+
+namespace headless {
+
+// A stub event source whose main purpose is to prevent the default platform
+// event source from getting created.
+class HeadlessPlatformEventSource : public ui::PlatformEventSource {
+ public:
+  HeadlessPlatformEventSource();
+  ~HeadlessPlatformEventSource() override;
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(HeadlessPlatformEventSource);
+};
+
+}  // namespace headless
+
+#endif  // HEADLESS_LIB_BROWSER_HEADLESS_PLATFORM_EVENT_SOURCE_H_