Refactor and cleanup codes. No functional changes.

util/gtl/BUILD

@@ -0,0 +1,19 @@
+################################################################################
+# Copyright 2017 Google LLC.
+#
+# This software is licensed under the terms defined in the Widevine Master
+# License Agreement. For a copy of this agreement, please contact
+# widevine-licensing@google.com.
+################################################################################
+
+package(
+    default_visibility = ["//visibility:public"],
+)
+
+
+cc_library(
+    name = "map_util",
+    hdrs = [
+        "map_util.h",
+    ],
+)

util/gtl/map_util.h

@@ -0,0 +1,58 @@
+////////////////////////////////////////////////////////////////////////////////
+// Copyright 2017 Google LLC.
+//
+// This software is licensed under the terms defined in the Widevine Master
+// License Agreement. For a copy of this agreement, please contact
+// widevine-licensing@google.com.
+////////////////////////////////////////////////////////////////////////////////
+
+#ifndef UTIL_GTL_MAP_UTIL_H_
+#define UTIL_GTL_MAP_UTIL_H_
+
+namespace widevine {
+namespace gtl {
+
+template <class Collection>
+const typename Collection::value_type::second_type& FindWithDefault(
+    const Collection& collection,
+    const typename Collection::value_type::first_type& key,
+    const typename Collection::value_type::second_type& value) {
+  typename Collection::const_iterator it = collection.find(key);
+  if (it == collection.end()) {
+    return value;
+  }
+  return it->second;
+}
+
+template <class Collection>
+typename Collection::value_type::second_type* FindOrNull(
+    const Collection& collection,
+    const typename Collection::value_type::first_type& key) {
+  typename Collection::iterator it = collection.find(key);
+  if (it == collection.end()) {
+    return nullptr;
+  }
+  return &it->second;
+}
+
+template <class Collection>
+typename Collection::value_type::second_type* FindOrNull(
+    Collection& collection,  // NOLINT
+    const typename Collection::value_type::first_type& key) {
+  typename Collection::iterator it = collection.find(key);
+  if (it == collection.end()) {
+    return nullptr;
+  }
+  return &it->second;
+}
+
+template <class C, class K>
+bool ContainsKey(const C& collection, const K& key) {
+  typename C::const_iterator it = collection.find(key);
+  return it != collection.end();
+}
+
+}  // namespace gtl
+}  // namespace widevine
+
+#endif  // UTIL_GTL_MAP_UTIL_H_