New script to count usage of C++ classes.

webrtc/tools/class_usage.sh

+#!/bin/bash
+
+# Copyright (c) 2017 The WebRTC project authors. All Rights Reserved.
+#
+# Use of this source code is governed by a BSD-style license
+# that can be found in the LICENSE file in the root of the source
+# tree. An additional intellectual property rights grant can be found
+# in the file PATENTS.  All contributing project authors may
+# be found in the AUTHORS file in the root of the source tree.
+
+# This script is run in a git repository. It lists all classes defined
+# in header files, sorted by the number of other files where the name
+# of the class occurs. It is intentionally not limited to only source
+# files. Classes close to the top of the list are candidates for
+# removal.
+
+git grep -h '^class .*[:{]' -- '*.h' '*.hpp' \
+  | sed -e 's/WEBRTC_DLL_EXPORT// ' -e 's/^class *\([^ :{(<]*\).*/\1/' \
+  | sort | uniq | while read class ; do
+  count="$(git grep -l -w -F "${class}" | wc -l)"
+  echo "${count}" "${class}"
+done | sort -n