Let lock_guard deduce its template argument

No functional change, this is a cleanup.

With C++17, it's no longer necessary to specify the teplate argument
when it can be deduced from the types of constructor arguments. This
allows de-cluttering our locking statements.

To avoid typos, this patch was mechanically generated:

  perl -p -i -e 's/std::lock_guard<std::mutex>/std::lock_guard/g' \
    $(find . -name '*.cpp' -o -name '*.h')

Change-Id: Ibb15d9a6c5b1c861d81353e47d25474eb1d4c2df
diff --git a/tests/dns_responder/dns_responder.cpp b/tests/dns_responder/dns_responder.cpp
index 0ba3388..615e6f6 100644
--- a/tests/dns_responder/dns_responder.cpp
+++ b/tests/dns_responder/dns_responder.cpp
@@ -538,7 +538,7 @@
 
 void DNSResponder::addMapping(const char* name, ns_type type,
         const char* addr) {
-    std::lock_guard<std::mutex> lock(mappings_mutex_);
+    std::lock_guard lock(mappings_mutex_);
     auto it = mappings_.find(QueryKey(name, type));
     if (it != mappings_.end()) {
         ALOGI("Overwriting mapping for (%s, %s), previous address %s, new "
@@ -553,7 +553,7 @@
 }
 
 void DNSResponder::removeMapping(const char* name, ns_type type) {
-    std::lock_guard<std::mutex> lock(mappings_mutex_);
+    std::lock_guard lock(mappings_mutex_);
     auto it = mappings_.find(QueryKey(name, type));
     if (it != mappings_.end()) {
         ALOGI("Cannot remove mapping mapping from (%s, %s), not present", name,
@@ -641,7 +641,7 @@
     epoll_fd_ = ep_fd;
     socket_ = s;
     {
-        std::lock_guard<std::mutex> lock(update_mutex_);
+        std::lock_guard lock(update_mutex_);
         handler_thread_ = std::thread(&DNSResponder::requestHandler, this);
     }
     ALOGI("server started successfully");
@@ -649,7 +649,7 @@
 }
 
 bool DNSResponder::stopServer() {
-    std::lock_guard<std::mutex> lock(update_mutex_);
+    std::lock_guard lock(update_mutex_);
     if (!running()) {
         ALOGI("server not running");
         return false;
@@ -670,12 +670,12 @@
 }
 
 std::vector<std::pair<std::string, ns_type >> DNSResponder::queries() const {
-    std::lock_guard<std::mutex> lock(queries_mutex_);
+    std::lock_guard lock(queries_mutex_);
     return queries_;
 }
 
 void DNSResponder::clearQueries() {
-    std::lock_guard<std::mutex> lock(queries_mutex_);
+    std::lock_guard lock(queries_mutex_);
     queries_.clear();
 }
 
@@ -765,7 +765,7 @@
                                  response_len);
     }
     {
-        std::lock_guard<std::mutex> lock(queries_mutex_);
+        std::lock_guard lock(queries_mutex_);
         for (const DNSQuestion& question : header.questions) {
             queries_.push_back(make_pair(question.qname.name,
                                          ns_type(question.qtype)));
@@ -808,7 +808,7 @@
 
 bool DNSResponder::addAnswerRecords(const DNSQuestion& question,
                                     std::vector<DNSRecord>* answers) const {
-    std::lock_guard<std::mutex> guard(mappings_mutex_);
+    std::lock_guard guard(mappings_mutex_);
     auto it = mappings_.find(QueryKey(question.qname.name, question.qtype));
     if (it == mappings_.end()) {
         // TODO(imaipi): handle correctly
diff --git a/tests/dns_responder/dns_tls_frontend.cpp b/tests/dns_responder/dns_tls_frontend.cpp
index 8c49254..b114280 100644
--- a/tests/dns_responder/dns_tls_frontend.cpp
+++ b/tests/dns_responder/dns_tls_frontend.cpp
@@ -256,7 +256,7 @@
     freeaddrinfo(backend_ai_res);
 
     {
-        std::lock_guard<std::mutex> lock(update_mutex_);
+        std::lock_guard lock(update_mutex_);
         handler_thread_ = std::thread(&DnsTlsFrontend::requestHandler, this);
     }
     ALOGI("server started successfully");
@@ -356,7 +356,7 @@
 }
 
 bool DnsTlsFrontend::stopServer() {
-    std::lock_guard<std::mutex> lock(update_mutex_);
+    std::lock_guard lock(update_mutex_);
     if (!running()) {
         ALOGI("server not running");
         return false;
diff --git a/tests/dns_tls_test.cpp b/tests/dns_tls_test.cpp
index ba71f24..cbedc34 100644
--- a/tests/dns_tls_test.cpp
+++ b/tests/dns_tls_test.cpp
@@ -186,13 +186,13 @@
 class FakeSocketDelay : public IDnsTlsSocket {
   public:
     explicit FakeSocketDelay(IDnsTlsSocketObserver* observer) : mObserver(observer) {}
-    ~FakeSocketDelay() { std::lock_guard<std::mutex> guard(mLock); }
+    ~FakeSocketDelay() { std::lock_guard guard(mLock); }
     static size_t sDelay;
     static bool sReverse;
 
     bool query(uint16_t id, const Slice query) override {
         ALOGD("FakeSocketDelay got query with ID %d", int(id));
-        std::lock_guard<std::mutex> guard(mLock);
+        std::lock_guard guard(mLock);
         // Check for duplicate IDs.
         EXPECT_EQ(0U, mIds.count(id));
         mIds.insert(id);
@@ -209,7 +209,7 @@
 
   private:
     void sendResponses() {
-        std::lock_guard<std::mutex> guard(mLock);
+        std::lock_guard guard(mLock);
         if (sReverse) {
             std::reverse(std::begin(mResponses), std::end(mResponses));
         }
@@ -423,7 +423,7 @@
     ~FakeSocketLimited() {
         {
             ALOGD("~FakeSocketLimited acquiring mLock");
-            std::lock_guard<std::mutex> guard(mLock);
+            std::lock_guard guard(mLock);
             ALOGD("~FakeSocketLimited acquired mLock");
             for (auto& thread : mThreads) {
                 ALOGD("~FakeSocketLimited joining response thread");
@@ -441,7 +441,7 @@
     }
     bool query(uint16_t id, const Slice query) override {
         ALOGD("FakeSocketLimited::query acquiring mLock");
-        std::lock_guard<std::mutex> guard(mLock);
+        std::lock_guard guard(mLock);
         ALOGD("FakeSocketLimited::query acquired mLock");
         ++mQueries;
 
@@ -462,7 +462,7 @@
     void sendClose() {
         {
             ALOGD("FakeSocketLimited::sendClose acquiring mLock");
-            std::lock_guard<std::mutex> guard(mLock);
+            std::lock_guard guard(mLock);
             ALOGD("FakeSocketLimited::sendClose acquired mLock");
             for (auto& thread : mThreads) {
                 ALOGD("FakeSocketLimited::sendClose joining response thread");
@@ -536,13 +536,13 @@
         mThreads.emplace_back(&IDnsTlsSocketObserver::onResponse, mObserver, make_query(ID + 1, SIZE));
     }
     ~FakeSocketGarbage() {
-        std::lock_guard<std::mutex> guard(mLock);
+        std::lock_guard guard(mLock);
         for (auto& thread : mThreads) {
             thread.join();
         }
     }
     bool query(uint16_t id, const Slice query) override {
-        std::lock_guard<std::mutex> guard(mLock);
+        std::lock_guard guard(mLock);
         // Return the response twice.
         auto echo = make_echo(id, query);
         mThreads.emplace_back(&IDnsTlsSocketObserver::onResponse, mObserver, echo);
@@ -608,7 +608,7 @@
             unsigned mark,
             IDnsTlsSocketObserver* observer,
             DnsTlsSessionCache* cache ATTRIBUTE_UNUSED) override {
-        std::lock_guard<std::mutex> guard(mLock);
+        std::lock_guard guard(mLock);
         keys.emplace(mark, server);
         return std::make_unique<T>(observer);
     }