Add UMA histograms and logging for bad IPC message handling

extensions/browser/bad_message.h

Index: extensions/browser/bad_message.h
diff --git a/extensions/browser/bad_message.h b/extensions/browser/bad_message.h
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+// Copyright 2015 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 EXTENSIONS_BROWSER_BAD_MESSAGE_H_
+#define EXTENSIONS_BROWSER_BAD_MESSAGE_H_
+
+namespace content {
+class RenderProcessHost;
+}
+
+namespace extensions {
+namespace bad_message {
+
+// The browser process often chooses to terminate a renderer if it receives
+// a bad IPC message. The reasons are tracked for metrics.
+//
+// See also content/browser/bad_message.h.
+//
+// NOTE: Do not remove or reorder elements in this list. Add new entries at the
+// end. Items may be renamed but do not change the values. We rely on the enum
+// values in histograms.
+enum BadMessageReason {
+  EOG_BAD_ORIGIN = 0,
+  EVG_BAD_ORIGIN,
+  BH_BLOB_NOT_OWNED,
+  EH_BAD_EVENT_ID,
+  // Please add new elements here. The naming convention is abbreviated class
+  // name (e.g. ExtensionHost becomes EH) plus a unique description of the
+  // reason.
+  BAD_MESSAGE_MAX
+};
+
+// Called when the browser receives a bad IPC message from an extension process.
+// Logs the event, records a histogram metric for the |reason|, and terminates
+// the process for |host|.
+void ReceivedBadMessage(content::RenderProcessHost* host,
+                        BadMessageReason reason);
+
+}  // bad_message
+}  // namespace extensions
+
+#endif  // EXTENSIONS_BROWSER_BAD_MESSAGE_H_