reland crrev.com/212927 Move webkitplatformsupport_impl and related from glue to child

webkit/child/webkit_child_helpers.h

Index: webkit/child/webkit_child_helpers.h
diff --git a/webkit/child/webkit_child_helpers.h b/webkit/child/webkit_child_helpers.h
new file mode 100644
index 0000000000000000000000000000000000000000..3262fa23138c999af64c762145c065f21eabf691
--- /dev/null
+++ b/webkit/child/webkit_child_helpers.h
@@ -0,0 +1,21 @@
+// Copyright (c) 2013 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 WEBKIT_CHILD_WEBKIT_CHILD_HELPERS_H_
+#define WEBKIT_CHILD_WEBKIT_CHILD_HELPERS_H_
+
+#include "base/basictypes.h"
+#include "webkit/child/webkit_child_export.h"
+
+namespace webkit_glue {
+
+// Returns an estimate of the memory usage of the renderer process. Different
+// platforms implement this function differently, and count in different
+// allocations. Results are not comparable across platforms. The estimate is
+// computed inside the sandbox and thus its not always accurate.
+WEBKIT_CHILD_EXPORT size_t MemoryUsageKB();
+
+}  // webkit_glue
+
+#endif  // WEBKIT_CHILD_WEBKIT_CHILD_HELPERS_H_