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/server/dns/DnsTlsDispatcher.cpp b/server/dns/DnsTlsDispatcher.cpp
index 95fbb9a..c336f54 100644
--- a/server/dns/DnsTlsDispatcher.cpp
+++ b/server/dns/DnsTlsDispatcher.cpp
@@ -44,7 +44,7 @@
     // Pull out any servers for which we might have existing connections and
     // place them at the from the list of servers to try.
     {
-        std::lock_guard<std::mutex> guard(sLock);
+        std::lock_guard guard(sLock);
 
         for (const auto& tlsServer : tlsServers) {
             const Key key = std::make_pair(mark, tlsServer);
@@ -113,7 +113,7 @@
     const Key key = std::make_pair(mark, server);
     Transport* xport;
     {
-        std::lock_guard<std::mutex> guard(sLock);
+        std::lock_guard guard(sLock);
         auto it = mStore.find(key);
         if (it == mStore.end()) {
             xport = new Transport(server, mark, mFactory.get());
@@ -144,7 +144,7 @@
 
     auto now = std::chrono::steady_clock::now();
     {
-        std::lock_guard<std::mutex> guard(sLock);
+        std::lock_guard guard(sLock);
         --xport->useCount;
         xport->lastUsed = now;
         cleanup(now);
diff --git a/server/dns/DnsTlsQueryMap.cpp b/server/dns/DnsTlsQueryMap.cpp
index 760b26a..2ef050c 100644
--- a/server/dns/DnsTlsQueryMap.cpp
+++ b/server/dns/DnsTlsQueryMap.cpp
@@ -25,7 +25,7 @@
 namespace net {
 
 std::unique_ptr<DnsTlsQueryMap::QueryFuture> DnsTlsQueryMap::recordQuery(const Slice query) {
-    std::lock_guard<std::mutex> guard(mLock);
+    std::lock_guard guard(mLock);
 
     // Store the query so it can be matched to the response or reissued.
     if (query.size() < 2) {
@@ -54,7 +54,7 @@
 }
 
 void DnsTlsQueryMap::markTried(uint16_t newId) {
-    std::lock_guard<std::mutex> guard(mLock);
+    std::lock_guard guard(mLock);
     auto it = mQueries.find(newId);
     if (it != mQueries.end()) {
         it->second.tries++;
@@ -62,7 +62,7 @@
 }
 
 void DnsTlsQueryMap::cleanup() {
-    std::lock_guard<std::mutex> guard(mLock);
+    std::lock_guard guard(mLock);
     for (auto it = mQueries.begin(); it != mQueries.end();) {
         auto& p = it->second;
         if (p.tries >= kMaxTries) {
@@ -101,7 +101,7 @@
 }
 
 std::vector<DnsTlsQueryMap::Query> DnsTlsQueryMap::getAll() {
-    std::lock_guard<std::mutex> guard(mLock);
+    std::lock_guard guard(mLock);
     std::vector<DnsTlsQueryMap::Query> queries;
     for (auto& q : mQueries) {
         queries.push_back(q.second.query);
@@ -110,12 +110,12 @@
 }
 
 bool DnsTlsQueryMap::empty() {
-    std::lock_guard<std::mutex> guard(mLock);
+    std::lock_guard guard(mLock);
     return mQueries.empty();
 }
 
 void DnsTlsQueryMap::clear() {
-    std::lock_guard<std::mutex> guard(mLock);
+    std::lock_guard guard(mLock);
     for (auto& q : mQueries) {
         expire(&q.second);
     }
@@ -129,7 +129,7 @@
         return;
     }
     uint16_t id = response[0] << 8 | response[1];
-    std::lock_guard<std::mutex> guard(mLock);
+    std::lock_guard guard(mLock);
     auto it = mQueries.find(id);
     if (it == mQueries.end()) {
         ALOGW("Discarding response: unknown ID %d", id);
diff --git a/server/dns/DnsTlsSessionCache.cpp b/server/dns/DnsTlsSessionCache.cpp
index 880b773..58e36b5 100644
--- a/server/dns/DnsTlsSessionCache.cpp
+++ b/server/dns/DnsTlsSessionCache.cpp
@@ -54,7 +54,7 @@
 }
 
 void DnsTlsSessionCache::recordSession(SSL_SESSION* session) {
-    std::lock_guard<std::mutex> guard(mLock);
+    std::lock_guard guard(mLock);
     mSessions.emplace_front(session);
     if (mSessions.size() > kMaxSize) {
         ALOGV("Too many sessions; trimming");
@@ -63,7 +63,7 @@
 }
 
 bssl::UniquePtr<SSL_SESSION> DnsTlsSessionCache::getSession() {
-    std::lock_guard<std::mutex> guard(mLock);
+    std::lock_guard guard(mLock);
     if (mSessions.size() == 0) {
         ALOGV("No known sessions");
         return nullptr;
diff --git a/server/dns/DnsTlsSocket.cpp b/server/dns/DnsTlsSocket.cpp
index 8e25b1f..df48d91 100644
--- a/server/dns/DnsTlsSocket.cpp
+++ b/server/dns/DnsTlsSocket.cpp
@@ -132,7 +132,7 @@
 bool DnsTlsSocket::initialize() {
     // This method should only be called once, at the beginning, so locking should be
     // unnecessary.  This lock only serves to help catch bugs in code that calls this method.
-    std::lock_guard<std::mutex> guard(mLock);
+    std::lock_guard guard(mLock);
     if (mSslCtx) {
         // This is a bug in the caller.
         return false;
@@ -340,7 +340,7 @@
 }
 
 void DnsTlsSocket::loop() {
-    std::lock_guard<std::mutex> guard(mLock);
+    std::lock_guard guard(mLock);
     // Buffer at most one query.
     Query q;
 
@@ -413,7 +413,7 @@
     mIpcInFd.reset();
     {
         // Wait for the orderly shutdown to complete.
-        std::lock_guard<std::mutex> guard(mLock);
+        std::lock_guard guard(mLock);
         if (mLoopThread && std::this_thread::get_id() == mLoopThread->get_id()) {
             ALOGE("Violation of re-entrance precondition");
             return;
diff --git a/server/dns/DnsTlsTransport.cpp b/server/dns/DnsTlsTransport.cpp
index 033ae80..e94daff 100644
--- a/server/dns/DnsTlsTransport.cpp
+++ b/server/dns/DnsTlsTransport.cpp
@@ -36,7 +36,7 @@
 namespace net {
 
 std::future<DnsTlsTransport::Result> DnsTlsTransport::query(const netdutils::Slice query) {
-    std::lock_guard<std::mutex> guard(mLock);
+    std::lock_guard guard(mLock);
 
     auto record = mQueries.recordQuery(query);
     if (!record) {
@@ -89,7 +89,7 @@
 }
 
 void DnsTlsTransport::onClosed() {
-    std::lock_guard<std::mutex> guard(mLock);
+    std::lock_guard guard(mLock);
     if (mClosing) {
         return;
     }
@@ -109,7 +109,7 @@
 }
 
 void DnsTlsTransport::doReconnect() {
-    std::lock_guard<std::mutex> guard(mLock);
+    std::lock_guard guard(mLock);
     if (mClosing) {
         return;
     }
@@ -126,7 +126,7 @@
 DnsTlsTransport::~DnsTlsTransport() {
     ALOGV("Destructor");
     {
-        std::lock_guard<std::mutex> guard(mLock);
+        std::lock_guard guard(mLock);
         ALOGV("Locked destruction procedure");
         mQueries.clear();
         mClosing = true;