[Mac] Modify the ObjC exception preprocessor to make some exceptions fatal.

chrome/browser/mac/exception_processor.h

+// 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 CHROME_BROWSER_MAC_EXCEPTION_PROCESSOR_H_
+#define CHROME_BROWSER_MAC_EXCEPTION_PROCESSOR_H_
+
+#include <stddef.h>
+
+@class NSException;
+
+namespace chrome {
+
+// Installs the Objective-C exception preprocessor. This records UMA and crash
+// keys for NSException objects. The preprocessor will also make fatal any
+// exception that is not handled.
+void InstallObjcExceptionPreprocessor();
+
+// The items below are exposed only for testing.
+////////////////////////////////////////////////////////////////////////////////
+
+// Removes the exception preprocessor if it is installed.
+void UninstallObjcExceptionPreprocessor();
+
+

[Mark Mentovai, 2016/12/01 19:02:32]

Extra blank line?

[Robert Sesek, 2016/12/06 23:18:09]

Done.

+// Bin for unknown exceptions. Exposed for testing purposes.

[Mark Mentovai, 2016/12/01 19:02:32]

“Exposed for testing purposes” on all of these isn’t necessary, because you’ve
put them into the “exposed only for testing” section titled above.

[Robert Sesek, 2016/12/06 23:18:09]

Done.

+extern const size_t kUnknownNSException;

[Mark Mentovai, 2016/12/01 19:02:32]

Can be constexpr and get its value right here?

[Robert Sesek, 2016/12/06 23:18:09]

Its value is kKnownNSExceptionCount, which isn't part of the header.

+
+// Returns the histogram bin for |exception| if it is one we track
+// specifically, or |kUnknownNSException| if unknown.  Exposed for testing
+// purposes.
+size_t BinForException(NSException* exception);
+
+// Use UMA to track exception occurance. Exposed for testing purposes.
+void RecordExceptionWithUma(NSException* exception);
+
+}  // namespace chrome
+
+#endif  // CHROME_BROWSER_MAC_EXCEPTION_PROCESSOR_H_