doc: Add documentation-generating scripts to the Crashpad tree

doc/generate_doxygen.sh

Index: doc/generate_doxygen.sh
diff --git a/util/test/paths_test_data_root.txt b/doc/generate_doxygen.sh
old mode 100644
new mode 100755
similarity index 68%
copy from util/test/paths_test_data_root.txt
copy to doc/generate_doxygen.sh
index 1ddd26425372bc5608b37c4379d140827b850301..5da9cd31ded211b04740200ca621e71310e51700
--- a/util/test/paths_test_data_root.txt
+++ b/doc/generate_doxygen.sh
@@ -1,3 +1,5 @@
+#!/bin/sh
+
 # Copyright 2015 The Crashpad Authors. All rights reserved.
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
@@ -12,5 +14,16 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-This file is used by Paths::TestDataRoot() to locate the test data root. It
-is present at a known path from the test data root.
+set -e
+
+# Generating Doxygen documentation requires Doxygen, http://www.doxygen.org/.
+
+# Run from the Crashpad project root directory.
+cd "$(dirname "${0}")/.."
+
+output_dir=out/doc/doxygen
+
+rm -rf "${output_dir}"
+mkdir -p "${output_dir}"
+
+doxygen doc/crashpad.doxy