Revert of Remove calls to MessageLoop::current() in content.

content/child/child_thread_impl.cc

Index: content/child/child_thread_impl.cc
diff --git a/content/child/child_thread_impl.cc b/content/child/child_thread_impl.cc
index 4db77a7dc71a0cee221e5b97512f8fd948e2c029..169c1e44fde694950329c8be9cee4d3074affc67 100644
--- a/content/child/child_thread_impl.cc
+++ b/content/child/child_thread_impl.cc
@@ -577,7 +577,7 @@
 }
 
 bool ChildThreadImpl::Send(IPC::Message* msg) {
-  DCHECK(message_loop_->task_runner()->BelongsToCurrentThread());
+  DCHECK(base::MessageLoop::current() == message_loop());
   if (!channel_) {
     delete msg;
     return false;
@@ -635,13 +635,13 @@
 }
 
 IPC::MessageRouter* ChildThreadImpl::GetRouter() {
-  DCHECK(message_loop_->task_runner()->BelongsToCurrentThread());
+  DCHECK(base::MessageLoop::current() == message_loop());
   return &router_;
 }
 
 std::unique_ptr<base::SharedMemory> ChildThreadImpl::AllocateSharedMemory(
     size_t buf_size) {
-  DCHECK(message_loop_->task_runner()->BelongsToCurrentThread());
+  DCHECK(base::MessageLoop::current() == message_loop());
   return AllocateSharedMemory(buf_size, this, nullptr);
 }