Provide a Mojo equivalent of ThreadSafeSender.

content/renderer/mojo/thread_safe_associated_interface_ptr_provider.h

Index: content/renderer/mojo/thread_safe_associated_interface_ptr_provider.h
diff --git a/content/renderer/mojo/thread_safe_associated_interface_ptr_provider.h b/content/renderer/mojo/thread_safe_associated_interface_ptr_provider.h
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+// Copyright 2016 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef CONTENT_RENDERER_MOJO_THREAD_SAFE_ASSOCIATED_INTERFACE_PTR_PROVIDER_H_
+#define CONTENT_RENDERER_MOJO_THREAD_SAFE_ASSOCIATED_INTERFACE_PTR_PROVIDER_H_
+
+#include "base/bind.h"
+#include "base/macros.h"
+#include "base/memory/ref_counted.h"
+#include "ipc/ipc_channel_proxy.h"
+#include "mojo/public/cpp/bindings/thread_safe_interface_ptr.h"
+
+namespace content {
+
+// This class provides a way to create ThreadSafeAssociatedInterfacePtr's from
+// the main thread that can be used right away (even though the backing
+// AssociatedInterfacePtr is created on the IO thread and the channel may not be
+// connected yet).
+class ThreadSafeAssociatedInterfacePtrProvider {
+ public:
+  // Note that this does not take ownership of |channel_proxy|. It's the
+  // caller responsibility to ensure |channel_proxy| outlives this object.
+  explicit ThreadSafeAssociatedInterfacePtrProvider(
+      IPC::ChannelProxy* channel_proxy)
+      : channel_proxy_(channel_proxy) {}
+
+  template <typename Interface>
+  scoped_refptr<mojo::ThreadSafeAssociatedInterfacePtr<Interface>>
+  CreateInterfacePtr() {
+    scoped_refptr<mojo::ThreadSafeAssociatedInterfacePtr<Interface>> ptr =
+        mojo::ThreadSafeAssociatedInterfacePtr<Interface>::CreateUnbound();
+    channel_proxy_->RetrieveAssociatedInterfaceOnIOThread<Interface>(base::Bind(
+        &ThreadSafeAssociatedInterfacePtrProvider::BindInterfacePtr<Interface>,
+        ptr));
+    return ptr;
+  }
+
+ private:
+  template <typename Interface>
+  static void BindInterfacePtr(
+      const scoped_refptr<mojo::ThreadSafeAssociatedInterfacePtr<Interface>>&
+          ptr,
+      mojo::AssociatedInterfacePtr<Interface> interface_ptr) {
+    bool success = ptr->Bind(std::move(interface_ptr));
+    DCHECK(success);
+  }
+
+  IPC::ChannelProxy* channel_proxy_;
+
+  DISALLOW_COPY_AND_ASSIGN(ThreadSafeAssociatedInterfacePtrProvider);
+};
+
+}  // namespace content
+
+#endif  // CONTENT_RENDERER_MOJO_THREAD_SAFE_ASSOCIATED_INTERFACE_PTR_PROVIDER_H_