Make nesting/running states a RunLoop rather than a MessageLoop concept.

mojo/public/cpp/bindings/lib/connector.cc

Index: mojo/public/cpp/bindings/lib/connector.cc
diff --git a/mojo/public/cpp/bindings/lib/connector.cc b/mojo/public/cpp/bindings/lib/connector.cc
index d93e45ed938cd9455222aed5855af75998408ab7..668894ce8dd086aa5248336a1908428fe7aff065 100644
--- a/mojo/public/cpp/bindings/lib/connector.cc
+++ b/mojo/public/cpp/bindings/lib/connector.cc
@@ -14,6 +14,7 @@
 #include "base/macros.h"
 #include "base/memory/ptr_util.h"
 #include "base/message_loop/message_loop.h"
+#include "base/run_loop.h"
 #include "base/synchronization/lock.h"
 #include "base/threading/thread_local.h"
 #include "mojo/public/cpp/bindings/lib/may_auto_lock.h"
@@ -27,9 +28,8 @@ namespace {
 // The NestingObserver for each thread. Note that this is always a
 // Connector::MessageLoopNestingObserver; we use the base type here because that
 // subclass is private to Connector.
-base::LazyInstance<
-    base::ThreadLocalPointer<base::MessageLoop::NestingObserver>>::Leaky
-    g_tls_nesting_observer = LAZY_INSTANCE_INITIALIZER;
+base::LazyInstance<base::ThreadLocalPointer<base::RunLoop::NestingObserver>>::
+    Leaky g_tls_nesting_observer = LAZY_INSTANCE_INITIALIZER;
 
 }  // namespace
 
@@ -54,17 +54,17 @@ class Connector::ActiveDispatchTracker {
 // Watches the MessageLoop on the current thread. Notifies the current chain of
 // ActiveDispatchTrackers when a nested message loop is started.
 class Connector::MessageLoopNestingObserver
-    : public base::MessageLoop::NestingObserver,
+    : public base::RunLoop::NestingObserver,
       public base::MessageLoop::DestructionObserver {
  public:
   MessageLoopNestingObserver() {
-    base::MessageLoop::current()->AddNestingObserver(this);
+    base::RunLoop::AddNestingObserverOnCurrentThread(this);
     base::MessageLoop::current()->AddDestructionObserver(this);
   }
 
   ~MessageLoopNestingObserver() override {}
 
-  // base::MessageLoop::NestingObserver:
+  // base::RunLoop::NestingObserver:
   void OnBeginNestedMessageLoop() override {
     if (top_tracker_)
       top_tracker_->NotifyBeginNesting();
@@ -72,7 +72,7 @@ class Connector::MessageLoopNestingObserver
 
   // base::MessageLoop::DestructionObserver:
   void WillDestroyCurrentMessageLoop() override {
-    base::MessageLoop::current()->RemoveNestingObserver(this);
+    base::RunLoop::RemoveNestingObserverOnCurrentThread(this);
     base::MessageLoop::current()->RemoveDestructionObserver(this);
     DCHECK_EQ(this, g_tls_nesting_observer.Get().Get());
     g_tls_nesting_observer.Get().Set(nullptr);
@@ -80,8 +80,7 @@ class Connector::MessageLoopNestingObserver
   }
 
   static MessageLoopNestingObserver* GetForThread() {
-    if (!base::MessageLoop::current() ||
-        !base::MessageLoop::current()->nesting_allowed())
+    if (!base::RunLoop::IsNestingAllowedOnCurrentThread())
       return nullptr;
     auto* observer = static_cast<MessageLoopNestingObserver*>(
         g_tls_nesting_observer.Get().Get());