Mojo: Dispatcher::MessageInTransitAccess functions don't need to take the lock.

mojo/system/dispatcher.cc

Index: mojo/system/dispatcher.cc
diff --git a/mojo/system/dispatcher.cc b/mojo/system/dispatcher.cc
index 233c03f0b2af78f66b14f0839347e59628db46ff..d2fb6b5a1de7fd033afa1090dfb43b3dc23a8bae 100644
--- a/mojo/system/dispatcher.cc
+++ b/mojo/system/dispatcher.cc
@@ -353,7 +353,7 @@ void Dispatcher::RemoveWaiterImplNoLock(Waiter* /*waiter*/) {
 
 size_t Dispatcher::GetMaximumSerializedSizeImplNoLock(
       const Channel* /*channel*/) const {
-  lock_.AssertAcquired();
+  DCHECK(HasOneRef());  // Only one ref => no need to take the lock.
   DCHECK(!is_closed_);
   // By default, serializing isn't supported.
   return 0;
@@ -362,7 +362,7 @@ size_t Dispatcher::GetMaximumSerializedSizeImplNoLock(
 bool Dispatcher::SerializeAndCloseImplNoLock(Channel* /*channel*/,
                                              void* /*destination*/,
                                              size_t* /*actual_size*/) {
-  lock_.AssertAcquired();
+  DCHECK(HasOneRef());  // Only one ref => no need to take the lock.
   DCHECK(is_closed_);
   // By default, serializing isn't supported, so just close.
   CloseImplNoLock();
@@ -398,9 +398,7 @@ Dispatcher::CreateEquivalentDispatcherAndCloseNoLock() {
 
 size_t Dispatcher::GetMaximumSerializedSize(const Channel* channel) const {
   DCHECK(channel);
-  DCHECK(HasOneRef());
-
-  base::AutoLock locker(lock_);
+  DCHECK(HasOneRef());  // Only one ref => no need to take the lock.
   DCHECK(!is_closed_);
   return GetMaximumSerializedSizeImplNoLock(channel);
 }
@@ -411,9 +409,7 @@ bool Dispatcher::SerializeAndClose(Channel* channel,
   DCHECK(destination);
   DCHECK(channel);
   DCHECK(actual_size);
-  DCHECK(HasOneRef());
-
-  base::AutoLock locker(lock_);
+  DCHECK(HasOneRef());  // Only one ref => no need to take the lock.
   DCHECK(!is_closed_);
 
   // We have to call |GetMaximumSerializedSizeImplNoLock()| first, because we