Mojo: Make |MojoAsyncWaiter|s const and remove the MojoAsyncWaiter* argument to AsyncWait/CancelWait.

The struct returned by GetDefaultAsyncWaiter() shouldn't be changed, and
the MojoAsyncWaiter* argument isn't interested or needed.

R=darin@chromium.org

Review URL: https://codereview.chromium.org/337813003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@277188 0039d316-1c4b-4281-b951-d872f2087c98

27 files changed, 59 insertions, 80 deletions

diff --git a/mojo/android/system/core_impl.cc b/mojo/android/system/core_impl.cc
index 1d7f879..366573c 100644
--- a/mojo/android/system/core_impl.cc
+++ b/mojo/android/system/core_impl.cc
@@ -329,13 +329,11 @@ static jobject AsyncWait(JNIEnv* env,
       new AsyncWaitCallbackData(env, jcaller, callback);
   MojoAsyncWaitID cancel_id;
   if (static_cast<MojoHandle>(mojo_handle) != MOJO_HANDLE_INVALID) {
-    MojoAsyncWaiter* async_waiter = mojo::GetDefaultAsyncWaiter();
-    cancel_id = async_waiter->AsyncWait(async_waiter,
-                                        mojo_handle,
-                                        flags,
-                                        deadline,
-                                        AsyncWaitCallback,
-                                        callback_data);
+    cancel_id = mojo::GetDefaultAsyncWaiter()->AsyncWait(mojo_handle,
+                                                         flags,
+                                                         deadline,
+                                                         AsyncWaitCallback,
+                                                         callback_data);
   } else {
     cancel_id = kInvalidHandleCancelID;
     base::MessageLoop::current()->PostTask(
@@ -362,8 +360,7 @@ static void CancelAsyncWait(JNIEnv* env,
   }
   scoped_ptr<AsyncWaitCallbackData> deleter(
       reinterpret_cast<AsyncWaitCallbackData*>(data_ptr));
-  MojoAsyncWaiter* async_waiter = mojo::GetDefaultAsyncWaiter();
-  async_waiter->CancelWait(async_waiter, id);
+  mojo::GetDefaultAsyncWaiter()->CancelWait(id);
 }
 
 bool RegisterCoreImpl(JNIEnv* env) {
diff --git a/mojo/bindings/js/waiting_callback.cc b/mojo/bindings/js/waiting_callback.cc
index ace0a76..597da44 100644
--- a/mojo/bindings/js/waiting_callback.cc
+++ b/mojo/bindings/js/waiting_callback.cc
@@ -28,9 +28,7 @@ gin::Handle<WaitingCallback> WaitingCallback::Create(
     MojoWaitFlags flags) {
   gin::Handle<WaitingCallback> waiting_callback =
       gin::CreateHandle(isolate, new WaitingCallback(isolate, callback));
-  MojoAsyncWaiter* waiter = GetDefaultAsyncWaiter();
-  waiting_callback->wait_id_ = waiter->AsyncWait(
-      waiter,
+  waiting_callback->wait_id_ = GetDefaultAsyncWaiter()->AsyncWait(
       handle.value(),
       flags,
       MOJO_DEADLINE_INDEFINITE,
@@ -43,8 +41,7 @@ void WaitingCallback::Cancel() {
   if (!wait_id_)
     return;
 
-  MojoAsyncWaiter* waiter = GetDefaultAsyncWaiter();
-  waiter->CancelWait(waiter, wait_id_);
+  GetDefaultAsyncWaiter()->CancelWait(wait_id_);
   wait_id_ = 0;
 }
 
diff --git a/mojo/environment/default_async_waiter.cc b/mojo/environment/default_async_waiter.cc
index bbd7229..092caec 100644
--- a/mojo/environment/default_async_waiter.cc
+++ b/mojo/environment/default_async_waiter.cc
@@ -8,7 +8,7 @@
 
 namespace mojo {
 
-MojoAsyncWaiter* GetDefaultAsyncWaiter() {
+const MojoAsyncWaiter* GetDefaultAsyncWaiter() {
   return internal::GetDefaultAsyncWaiterImpl();
 }
 
diff --git a/mojo/environment/default_async_waiter_impl.cc b/mojo/environment/default_async_waiter_impl.cc
index 576dd98..5279aad 100644
--- a/mojo/environment/default_async_waiter_impl.cc
+++ b/mojo/environment/default_async_waiter_impl.cc
@@ -19,8 +19,7 @@ void OnHandleReady(common::HandleWatcher* watcher,
   callback(closure, result);
 }
 
-MojoAsyncWaitID AsyncWait(MojoAsyncWaiter* waiter,
-                          MojoHandle handle,
+MojoAsyncWaitID AsyncWait(MojoHandle handle,
                           MojoWaitFlags flags,
                           MojoDeadline deadline,
                           MojoAsyncWaitCallback callback,
@@ -32,19 +31,19 @@ MojoAsyncWaitID AsyncWait(MojoAsyncWaiter* waiter,
   return reinterpret_cast<MojoAsyncWaitID>(watcher);
 }
 
-void CancelWait(MojoAsyncWaiter* waiter, MojoAsyncWaitID wait_id) {
+void CancelWait(MojoAsyncWaitID wait_id) {
   delete reinterpret_cast<common::HandleWatcher*>(wait_id);
 }
 
-MojoAsyncWaiter s_default_async_waiter = {
+const MojoAsyncWaiter kDefaultAsyncWaiter = {
   AsyncWait,
   CancelWait
 };
 
 }  // namespace
 
-MojoAsyncWaiter* GetDefaultAsyncWaiterImpl() {
-  return &s_default_async_waiter;
+const MojoAsyncWaiter* GetDefaultAsyncWaiterImpl() {
+  return &kDefaultAsyncWaiter;
 }
 
 }  // namespace internal
diff --git a/mojo/environment/default_async_waiter_impl.h b/mojo/environment/default_async_waiter_impl.h
index 8e697cb..5140e35 100644
--- a/mojo/environment/default_async_waiter_impl.h
+++ b/mojo/environment/default_async_waiter_impl.h
@@ -11,7 +11,7 @@
 namespace mojo {
 namespace internal {
 
-MOJO_ENVIRONMENT_IMPL_EXPORT MojoAsyncWaiter* GetDefaultAsyncWaiterImpl();
+MOJO_ENVIRONMENT_IMPL_EXPORT const MojoAsyncWaiter* GetDefaultAsyncWaiterImpl();
 
 }  // namespace internal
 }  // namespace mojo
diff --git a/mojo/gles2/command_buffer_client_impl.cc b/mojo/gles2/command_buffer_client_impl.cc
index c051ac2..975233b 100644
--- a/mojo/gles2/command_buffer_client_impl.cc
+++ b/mojo/gles2/command_buffer_client_impl.cc
@@ -48,7 +48,7 @@ void CommandBufferDelegate::DrawAnimationFrame() {}
 
 CommandBufferClientImpl::CommandBufferClientImpl(
     CommandBufferDelegate* delegate,
-    MojoAsyncWaiter* async_waiter,
+    const MojoAsyncWaiter* async_waiter,
     ScopedMessagePipeHandle command_buffer_handle)
     : delegate_(delegate),
       shared_state_(NULL),
diff --git a/mojo/gles2/command_buffer_client_impl.h b/mojo/gles2/command_buffer_client_impl.h
index e4c7893..6c5c433 100644
--- a/mojo/gles2/command_buffer_client_impl.h
+++ b/mojo/gles2/command_buffer_client_impl.h
@@ -41,7 +41,7 @@ class CommandBufferClientImpl : public CommandBufferClient,
  public:
   explicit CommandBufferClientImpl(
       CommandBufferDelegate* delegate,
-      MojoAsyncWaiter* async_waiter,
+      const MojoAsyncWaiter* async_waiter,
       ScopedMessagePipeHandle command_buffer_handle);
   virtual ~CommandBufferClientImpl();
 
@@ -107,7 +107,7 @@ class CommandBufferClientImpl : public CommandBufferClient,
   int32 next_transfer_buffer_id_;
 
   bool initialize_result_;
-  MojoAsyncWaiter* async_waiter_;
+  const MojoAsyncWaiter* async_waiter_;
 };
 
 }  // gles2
diff --git a/mojo/gles2/gles2_context.cc b/mojo/gles2/gles2_context.cc
index 78e5168..701b0fe 100644
--- a/mojo/gles2/gles2_context.cc
+++ b/mojo/gles2/gles2_context.cc
@@ -20,7 +20,7 @@ const size_t kDefaultMinTransferBufferSize = 1 * 256 * 1024;
 const size_t kDefaultMaxTransferBufferSize = 16 * 1024 * 1024;
 }
 
-GLES2Context::GLES2Context(MojoAsyncWaiter* async_waiter,
+GLES2Context::GLES2Context(const MojoAsyncWaiter* async_waiter,
                            ScopedMessagePipeHandle command_buffer_handle,
                            MojoGLES2ContextLost lost_callback,
                            MojoGLES2DrawAnimationFrame animation_callback,
diff --git a/mojo/gles2/gles2_context.h b/mojo/gles2/gles2_context.h
index 9f5ff7d..bc73082 100644
--- a/mojo/gles2/gles2_context.h
+++ b/mojo/gles2/gles2_context.h
@@ -27,7 +27,7 @@ namespace gles2 {
 class GLES2Context : public CommandBufferDelegate,
                      public MojoGLES2ContextPrivate {
  public:
-  explicit GLES2Context(MojoAsyncWaiter* async_waiter,
+  explicit GLES2Context(const MojoAsyncWaiter* async_waiter,
                         ScopedMessagePipeHandle command_buffer_handle,
                         MojoGLES2ContextLost lost_callback,
                         MojoGLES2DrawAnimationFrame animation_callback,
diff --git a/mojo/gles2/gles2_support_impl.cc b/mojo/gles2/gles2_support_impl.cc
index c348219..7fd8608 100644
--- a/mojo/gles2/gles2_support_impl.cc
+++ b/mojo/gles2/gles2_support_impl.cc
@@ -47,7 +47,7 @@ GLES2SupportImpl::~GLES2SupportImpl() {}
 // static
 void GLES2SupportImpl::Init() { GLES2Support::Init(new GLES2SupportImpl()); }
 
-void GLES2SupportImpl::Initialize(MojoAsyncWaiter* async_waiter) {
+void GLES2SupportImpl::Initialize(const MojoAsyncWaiter* async_waiter) {
   DCHECK(!async_waiter_);
   DCHECK(async_waiter);
   async_waiter_ = async_waiter;
diff --git a/mojo/gles2/gles2_support_impl.h b/mojo/gles2/gles2_support_impl.h
index a57000d..3305bf6 100644
--- a/mojo/gles2/gles2_support_impl.h
+++ b/mojo/gles2/gles2_support_impl.h
@@ -18,7 +18,7 @@ class MOJO_GLES2_IMPL_EXPORT GLES2SupportImpl : public GLES2Support {
 
   static void Init();
 
-  virtual void Initialize(MojoAsyncWaiter* async_waiter) OVERRIDE;
+  virtual void Initialize(const MojoAsyncWaiter* async_waiter) OVERRIDE;
   virtual void Terminate() OVERRIDE;
   virtual MojoGLES2Context CreateContext(
       MessagePipeHandle handle,
@@ -37,7 +37,7 @@ class MOJO_GLES2_IMPL_EXPORT GLES2SupportImpl : public GLES2Support {
  private:
   GLES2SupportImpl();
 
-  MojoAsyncWaiter* async_waiter_;
+  const MojoAsyncWaiter* async_waiter_;
 };
 
 }  // namespace gles2
diff --git a/mojo/public/c/environment/async_waiter.h b/mojo/public/c/environment/async_waiter.h
index a28340a..a330b64 100644
--- a/mojo/public/c/environment/async_waiter.h
+++ b/mojo/public/c/environment/async_waiter.h
@@ -7,10 +7,6 @@
 
 #include "mojo/public/c/system/types.h"
 
-#ifdef __cplusplus
-extern "C" {
-#endif
-
 typedef uintptr_t MojoAsyncWaitID;
 
 typedef void (*MojoAsyncWaitCallback)(void* closure, MojoResult result);
@@ -20,8 +16,7 @@ struct MojoAsyncWaiter {
   // of MojoWait to the given MojoAsyncWaitCallback on the current thread.
   // Returns a non-zero MojoAsyncWaitID that can be used with CancelWait to
   // stop waiting. This identifier becomes invalid once the callback runs.
-  MojoAsyncWaitID (*AsyncWait)(struct MojoAsyncWaiter* waiter,
-                               MojoHandle handle,
+  MojoAsyncWaitID (*AsyncWait)(MojoHandle handle,
                                MojoWaitFlags flags,
                                MojoDeadline deadline,
                                MojoAsyncWaitCallback callback,
@@ -29,12 +24,7 @@ struct MojoAsyncWaiter {
 
   // Cancel an existing call to AsyncWait with the given MojoAsyncWaitID. The
   // corresponding MojoAsyncWaitCallback will not be called in this case.
-  void (*CancelWait)(struct MojoAsyncWaiter* waiter,
-                     MojoAsyncWaitID wait_id);
+  void (*CancelWait)(MojoAsyncWaitID wait_id);
 };
 
-#ifdef __cplusplus
-}  // extern "C"
-#endif
-
 #endif  // MOJO_PUBLIC_C_ENVIRONMENT_ASYNC_WAITER_H_
diff --git a/mojo/public/c/gles2/gles2.h b/mojo/public/c/gles2/gles2.h
index 6b71d65..9763d34 100644
--- a/mojo/public/c/gles2/gles2.h
+++ b/mojo/public/c/gles2/gles2.h
@@ -19,7 +19,7 @@
 extern "C" {
 #endif
 
-MOJO_GLES2_EXPORT void MojoGLES2Initialize(MojoAsyncWaiter* async_waiter);
+MOJO_GLES2_EXPORT void MojoGLES2Initialize(const MojoAsyncWaiter* async_waiter);
 MOJO_GLES2_EXPORT void MojoGLES2Terminate();
 MOJO_GLES2_EXPORT MojoGLES2Context MojoGLES2CreateContext(
     MojoHandle handle,
diff --git a/mojo/public/cpp/bindings/interface_impl.h b/mojo/public/cpp/bindings/interface_impl.h
index a7272b6..6e68aa7 100644
--- a/mojo/public/cpp/bindings/interface_impl.h
+++ b/mojo/public/cpp/bindings/interface_impl.h
@@ -59,7 +59,7 @@ class InterfaceImpl : public internal::InterfaceImplBase<Interface> {
 template <typename Impl>
 Impl* BindToPipe(Impl* instance,
                  ScopedMessagePipeHandle handle,
-                 MojoAsyncWaiter* waiter = GetDefaultAsyncWaiter()) {
+                 const MojoAsyncWaiter* waiter = GetDefaultAsyncWaiter()) {
   instance->internal_state()->Bind(handle.Pass(), waiter);
   return instance;
 }
@@ -77,7 +77,7 @@ Impl* BindToPipe(Impl* instance,
 template <typename Impl, typename Interface>
 Impl* BindToProxy(Impl* instance,
                   InterfacePtr<Interface>* ptr,
-                  MojoAsyncWaiter* waiter = GetDefaultAsyncWaiter()) {
+                  const MojoAsyncWaiter* waiter = GetDefaultAsyncWaiter()) {
   instance->internal_state()->BindProxy(ptr, waiter);
   return instance;
 }
@@ -96,7 +96,7 @@ Impl* BindToProxy(Impl* instance,
 template <typename Impl, typename Interface>
 Impl* BindToRequest(Impl* instance,
                     InterfaceRequest<Interface>* request,
-                    MojoAsyncWaiter* waiter = GetDefaultAsyncWaiter()) {
+                    const MojoAsyncWaiter* waiter = GetDefaultAsyncWaiter()) {
   return BindToPipe(instance, request->PassMessagePipe(), waiter);
 }
 
diff --git a/mojo/public/cpp/bindings/interface_ptr.h b/mojo/public/cpp/bindings/interface_ptr.h
index 266cda0..8359319 100644
--- a/mojo/public/cpp/bindings/interface_ptr.h
+++ b/mojo/public/cpp/bindings/interface_ptr.h
@@ -56,7 +56,7 @@ class InterfacePtr {
   // thread, and bind the new InterfacePtr<..> to the message pipe on that
   // thread.
   void Bind(ScopedMessagePipeHandle handle,
-            MojoAsyncWaiter* waiter = GetDefaultAsyncWaiter()) {
+            const MojoAsyncWaiter* waiter = GetDefaultAsyncWaiter()) {
     reset();
     internal_state_.ConfigureProxy(handle.Pass(), waiter);
   }
@@ -110,7 +110,7 @@ class InterfacePtr {
 template <typename Interface>
 InterfacePtr<Interface> MakeProxy(
     ScopedMessagePipeHandle handle,
-    MojoAsyncWaiter* waiter = GetDefaultAsyncWaiter()) {
+    const MojoAsyncWaiter* waiter = GetDefaultAsyncWaiter()) {
   InterfacePtr<Interface> ptr;
   if (handle.is_valid())
     ptr.Bind(handle.Pass(), waiter);
diff --git a/mojo/public/cpp/bindings/lib/connector.cc b/mojo/public/cpp/bindings/lib/connector.cc
index f113058..8b97ff7 100644
--- a/mojo/public/cpp/bindings/lib/connector.cc
+++ b/mojo/public/cpp/bindings/lib/connector.cc
@@ -15,7 +15,7 @@ namespace internal {
 // ----------------------------------------------------------------------------
 
 Connector::Connector(ScopedMessagePipeHandle message_pipe,
-                     MojoAsyncWaiter* waiter)
+                     const MojoAsyncWaiter* waiter)
     : error_handler_(NULL),
       waiter_(waiter),
       message_pipe_(message_pipe.Pass()),
@@ -31,7 +31,7 @@ Connector::Connector(ScopedMessagePipeHandle message_pipe,
 
 Connector::~Connector() {
   if (async_wait_id_)
-    waiter_->CancelWait(waiter_, async_wait_id_);
+    waiter_->CancelWait(async_wait_id_);
 }
 
 void Connector::CloseMessagePipe() {
@@ -40,7 +40,7 @@ void Connector::CloseMessagePipe() {
 
 ScopedMessagePipeHandle Connector::PassMessagePipe() {
   if (async_wait_id_) {
-    waiter_->CancelWait(waiter_, async_wait_id_);
+    waiter_->CancelWait(async_wait_id_);
     async_wait_id_ = 0;
   }
   return message_pipe_.Pass();
@@ -107,8 +107,7 @@ void Connector::OnHandleReady(MojoResult result) {
 }
 
 void Connector::WaitToReadMore() {
-  async_wait_id_ = waiter_->AsyncWait(waiter_,
-                                      message_pipe_.get().value(),
+  async_wait_id_ = waiter_->AsyncWait(message_pipe_.get().value(),
                                       MOJO_WAIT_FLAG_READABLE,
                                       MOJO_DEADLINE_INDEFINITE,
                                       &Connector::CallOnHandleReady,
diff --git a/mojo/public/cpp/bindings/lib/connector.h b/mojo/public/cpp/bindings/lib/connector.h
index c7077b6..ef503d4 100644
--- a/mojo/public/cpp/bindings/lib/connector.h
+++ b/mojo/public/cpp/bindings/lib/connector.h
@@ -26,7 +26,7 @@ class Connector : public MessageReceiver {
  public:
   // The Connector takes ownership of |message_pipe|.
   explicit Connector(ScopedMessagePipeHandle message_pipe,
-                     MojoAsyncWaiter* waiter = GetDefaultAsyncWaiter());
+                     const MojoAsyncWaiter* waiter = GetDefaultAsyncWaiter());
   virtual ~Connector();
 
   // Sets the receiver to handle messages read from the message pipe.  The
@@ -72,7 +72,7 @@ class Connector : public MessageReceiver {
   void ReadMore();
 
   ErrorHandler* error_handler_;
-  MojoAsyncWaiter* waiter_;
+  const MojoAsyncWaiter* waiter_;
 
   ScopedMessagePipeHandle message_pipe_;
   MessageReceiver* incoming_receiver_;
diff --git a/mojo/public/cpp/bindings/lib/interface_impl_internal.h b/mojo/public/cpp/bindings/lib/interface_impl_internal.h
index bf770c1..79b598d 100644
--- a/mojo/public/cpp/bindings/lib/interface_impl_internal.h
+++ b/mojo/public/cpp/bindings/lib/interface_impl_internal.h
@@ -44,14 +44,14 @@ class InterfaceImplState : public ErrorHandler {
 
   void BindProxy(
       InterfacePtr<Interface>* ptr,
-      MojoAsyncWaiter* waiter = GetDefaultAsyncWaiter()) {
+      const MojoAsyncWaiter* waiter = GetDefaultAsyncWaiter()) {
     MessagePipe pipe;
     ptr->Bind(pipe.handle0.Pass(), waiter);
     Bind(pipe.handle1.Pass(), waiter);
   }
 
   void Bind(ScopedMessagePipeHandle handle,
-            MojoAsyncWaiter* waiter) {
+            const MojoAsyncWaiter* waiter) {
     assert(!router_);
 
     FilterChain filters;
diff --git a/mojo/public/cpp/bindings/lib/interface_ptr_internal.h b/mojo/public/cpp/bindings/lib/interface_ptr_internal.h
index 4bcaa64..607791c 100644
--- a/mojo/public/cpp/bindings/lib/interface_ptr_internal.h
+++ b/mojo/public/cpp/bindings/lib/interface_ptr_internal.h
@@ -38,7 +38,7 @@ class InterfacePtrState {
   }
 
   void ConfigureProxy(ScopedMessagePipeHandle handle,
-                      MojoAsyncWaiter* waiter = GetDefaultAsyncWaiter()) {
+                      const MojoAsyncWaiter* waiter = GetDefaultAsyncWaiter()) {
     assert(!proxy_);
     assert(!router_);
 
diff --git a/mojo/public/cpp/bindings/lib/router.cc b/mojo/public/cpp/bindings/lib/router.cc
index 7d0d868..27510e7 100644
--- a/mojo/public/cpp/bindings/lib/router.cc
+++ b/mojo/public/cpp/bindings/lib/router.cc
@@ -51,7 +51,7 @@ bool Router::HandleIncomingMessageThunk::Accept(Message* message) {
 
 Router::Router(ScopedMessagePipeHandle message_pipe,
                FilterChain filters,
-               MojoAsyncWaiter* waiter)
+               const MojoAsyncWaiter* waiter)
     : thunk_(this),
       filters_(filters.Pass()),
       connector_(message_pipe.Pass(), waiter),
diff --git a/mojo/public/cpp/bindings/lib/router.h b/mojo/public/cpp/bindings/lib/router.h
index 4a487d7..e30b924 100644
--- a/mojo/public/cpp/bindings/lib/router.h
+++ b/mojo/public/cpp/bindings/lib/router.h
@@ -18,7 +18,7 @@ class Router : public MessageReceiverWithResponder {
  public:
   Router(ScopedMessagePipeHandle message_pipe,
          FilterChain filters,
-         MojoAsyncWaiter* waiter = GetDefaultAsyncWaiter());
+         const MojoAsyncWaiter* waiter = GetDefaultAsyncWaiter());
   virtual ~Router();
 
   // Sets the receiver to handle messages read from the message pipe that do
diff --git a/mojo/public/cpp/environment/default_async_waiter.h b/mojo/public/cpp/environment/default_async_waiter.h
index 6edfaaa..fa87648 100644
--- a/mojo/public/cpp/environment/default_async_waiter.h
+++ b/mojo/public/cpp/environment/default_async_waiter.h
@@ -9,8 +9,8 @@
 
 namespace mojo {
 
-// Returns a default implementation of MojoAsyncWaiter.
-MojoAsyncWaiter* GetDefaultAsyncWaiter();
+// Returns a default implementation of |MojoAsyncWaiter|.
+const MojoAsyncWaiter* GetDefaultAsyncWaiter();
 
 }  // namespace mojo
 
diff --git a/mojo/public/cpp/environment/lib/default_async_waiter.cc b/mojo/public/cpp/environment/lib/default_async_waiter.cc
index 73e41de..4dcbe47 100644
--- a/mojo/public/cpp/environment/lib/default_async_waiter.cc
+++ b/mojo/public/cpp/environment/lib/default_async_waiter.cc
@@ -58,8 +58,7 @@ class RunLoopHandlerImpl : public RunLoopHandler {
   MOJO_DISALLOW_COPY_AND_ASSIGN(RunLoopHandlerImpl);
 };
 
-MojoAsyncWaitID AsyncWait(MojoAsyncWaiter* waiter,
-                          MojoHandle handle,
+MojoAsyncWaitID AsyncWait(MojoHandle handle,
                           MojoWaitFlags flags,
                           MojoDeadline deadline,
                           MojoAsyncWaitCallback callback,
@@ -75,19 +74,19 @@ MojoAsyncWaitID AsyncWait(MojoAsyncWaiter* waiter,
   return reinterpret_cast<MojoAsyncWaitID>(run_loop_handler);
 }
 
-void CancelWait(MojoAsyncWaiter* waiter, MojoAsyncWaitID wait_id) {
+void CancelWait(MojoAsyncWaitID wait_id) {
   delete reinterpret_cast<RunLoopHandlerImpl*>(wait_id);
 }
 
-MojoAsyncWaiter s_default_async_waiter = {
+const MojoAsyncWaiter kDefaultAsyncWaiter = {
   AsyncWait,
   CancelWait
 };
 
 }  // namespace
 
-MojoAsyncWaiter* GetDefaultAsyncWaiter() {
-  return &s_default_async_waiter;
+const MojoAsyncWaiter* GetDefaultAsyncWaiter() {
+  return &kDefaultAsyncWaiter;
 }
 
 }  // namespace mojo
diff --git a/mojo/public/cpp/environment/tests/async_waiter_unittest.cc b/mojo/public/cpp/environment/tests/async_waiter_unittest.cc
index 75cefb2..7943a5d 100644
--- a/mojo/public/cpp/environment/tests/async_waiter_unittest.cc
+++ b/mojo/public/cpp/environment/tests/async_waiter_unittest.cc
@@ -42,18 +42,16 @@ class TestAsyncWaitCallback {
 MojoAsyncWaitID CallAsyncWait(const Handle& handle,
                               MojoWaitFlags flags,
                               TestAsyncWaitCallback* callback) {
-  MojoAsyncWaiter* waiter = GetDefaultAsyncWaiter();
-  return waiter->AsyncWait(waiter,
-                           handle.value(),
-                           flags,
-                           MOJO_DEADLINE_INDEFINITE,
-                           &TestAsyncWaitCallback::OnHandleReady,
-                           callback);
+  return GetDefaultAsyncWaiter()->AsyncWait(
+      handle.value(),
+      flags,
+      MOJO_DEADLINE_INDEFINITE,
+      &TestAsyncWaitCallback::OnHandleReady,
+      callback);
 }
 
 void CallCancelWait(MojoAsyncWaitID wait_id) {
-  MojoAsyncWaiter* waiter = GetDefaultAsyncWaiter();
-  waiter->CancelWait(waiter, wait_id);
+  GetDefaultAsyncWaiter()->CancelWait(wait_id);
 }
 
 class AsyncWaiterTest : public testing::Test {
diff --git a/mojo/public/cpp/gles2/gles2.h b/mojo/public/cpp/gles2/gles2.h
index cf6686c..4c1156e 100644
--- a/mojo/public/cpp/gles2/gles2.h
+++ b/mojo/public/cpp/gles2/gles2.h
@@ -13,7 +13,7 @@ namespace mojo {
 class GLES2Initializer {
  public:
   explicit GLES2Initializer(
-      MojoAsyncWaiter* async_waiter = GetDefaultAsyncWaiter()) {
+      const MojoAsyncWaiter* async_waiter = GetDefaultAsyncWaiter()) {
     MojoGLES2Initialize(async_waiter);
   }
   ~GLES2Initializer() { MojoGLES2Terminate(); }
diff --git a/mojo/public/gles2/gles2_private.cc b/mojo/public/gles2/gles2_private.cc
index 7887349..52b47d3 100644
--- a/mojo/public/gles2/gles2_private.cc
+++ b/mojo/public/gles2/gles2_private.cc
@@ -15,7 +15,7 @@ static mojo::GLES2Interface* g_gles2_interface = NULL;
 
 extern "C" {
 
-void MojoGLES2Initialize(MojoAsyncWaiter* async_waiter) {
+void MojoGLES2Initialize(const MojoAsyncWaiter* async_waiter) {
   assert(g_gles2_support);
   return g_gles2_support->Initialize(async_waiter);
 }
diff --git a/mojo/public/gles2/gles2_private.h b/mojo/public/gles2/gles2_private.h
index c92f555..f0a336d6 100644
--- a/mojo/public/gles2/gles2_private.h
+++ b/mojo/public/gles2/gles2_private.h
@@ -24,7 +24,7 @@ class MOJO_GLES2_EXPORT GLES2Support {
 
   static void Init(GLES2Support* gles2_support);
 
-  virtual void Initialize(MojoAsyncWaiter* async_waiter) = 0;
+  virtual void Initialize(const MojoAsyncWaiter* async_waiter) = 0;
   virtual void Terminate() = 0;
   virtual MojoGLES2Context CreateContext(
       MessagePipeHandle handle,