Re-committing http://codereview.chromium.org/6803005/ after fixing multi-dll build:

third_party/libphonenumber/cpp/src/re2_cache.cc

+// Copyright (C) 2011 Google Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// Author: Fredrik Roubert <roubert@google.com>
+
+#include "re2_cache.h"
+
+#include <cstddef>
+#include <string>
+#include <utility>
+
+#include <re2/re2.h>
+
+#include "base/logging.h"
+#include "base/synchronization/lock.h"
+
+using std::string;
+
+// A basic text book string hash function implementation, this one taken from
+// The Practice of Programming (Kernighan and Pike 1999). It could be a good
+// idea in the future to evaluate how well it actually performs and possibly
+// switch to another hash function better suited to this particular use case.
+namespace __gnu_cxx {
+template<> struct hash<string> {
+  enum { MULTIPLIER = 31 };
+  size_t operator()(const string& key) const {
+    size_t h = 0;
+    for (const char* p = key.c_str(); *p != '\0'; ++p) {
+      h *= MULTIPLIER;
+      h += *p;
+    }
+    return h;
+  }
+};
+}  // namespace __gnu_cxx
+
+namespace i18n {
+namespace phonenumbers {
+
+RE2Cache::RE2Cache(size_t min_items) : cache_impl_(new CacheImpl(min_items)) {}
+RE2Cache::~RE2Cache() {
+  base::AutoLock l(lock_);
+  LOG(2) << "Cache entries upon destruction: " << cache_impl_->size();
+  for (CacheImpl::const_iterator
+       it = cache_impl_->begin(); it != cache_impl_->end(); ++it) {
+    delete it->second;
+  }
+}
+
+RE2Cache::ScopedAccess::ScopedAccess(RE2Cache* cache, const string& pattern) {
+  DCHECK(cache);
+  base::AutoLock l(cache->lock_);
+  CacheImpl* const cache_impl = cache->cache_impl_.get();
+  CacheImpl::const_iterator it = cache_impl->find(pattern);
+  if (it != cache_impl->end()) {
+    regexp_ = it->second;
+  } else {
+    regexp_ = new RE2(pattern);
+    cache_impl->insert(make_pair(pattern, regexp_));
+  }
+}
+
+}  // namespace phonenumbers
+}  // namespace i18n