Add BlimpDocument, pull out functions in BlimpCompositor.

blimp/client/core/render_widget/blimp_document.h

Index: blimp/client/core/render_widget/blimp_document.h
diff --git a/blimp/client/core/render_widget/blimp_document.h b/blimp/client/core/render_widget/blimp_document.h
new file mode 100644
index 0000000000000000000000000000000000000000..d03b7d172f465306efc419cea45658890903ab8b
--- /dev/null
+++ b/blimp/client/core/render_widget/blimp_document.h
@@ -0,0 +1,60 @@
+// 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 BLIMP_CLIENT_CORE_RENDER_WIDGET_BLIMP_DOCUMENT_H_
+#define BLIMP_CLIENT_CORE_RENDER_WIDGET_BLIMP_DOCUMENT_H_
+
+#include <memory>
+
+#include "base/macros.h"
+#include "base/memory/ptr_util.h"
+#include "blimp/client/core/compositor/blimp_compositor.h"
+
+namespace blimp {
+namespace client {
+
+class BlimpCompositorDependencies;
+class BlimpDocumentManager;
+
+// BlimpDocument maps to an engine side render widget.
+// 1. Is created on receiving an RenderWidgetMessage from the engine.
+// 2. Owns the BlimpCompositor instance.
+class BlimpDocument : public BlimpCompositorClient {
+ public:
+  BlimpDocument(int document_id,
+                BlimpCompositorDependencies* compositor_dependencies,
+                BlimpDocumentManager* document_manager);
+  ~BlimpDocument() override;
+
+  int document_id() const { return document_id_; }
+
+  // Returns the compositor instance.
+  BlimpCompositor* GetCompositor();
+
+ protected:
+  void SetCompositorForTest(std::unique_ptr<BlimpCompositor> compositor);
+
+ private:
+  // BlimpCompositorClient implementation.
+  void SendWebGestureEvent(
+      const blink::WebGestureEvent& gesture_event) override;
+  void SendCompositorMessage(
+      const cc::proto::CompositorMessage& message) override;
+
+  // The unique identifier for this document instance.
+  const int document_id_;
+
+  // The compositor instance.
+  std::unique_ptr<BlimpCompositor> compositor_;
+
+  // Used to send messages to the corresponding render widget on the engine.
+  BlimpDocumentManager* manager_;
+
+  DISALLOW_COPY_AND_ASSIGN(BlimpDocument);
+};
+
+}  // namespace client
+}  // namespace blimp
+
+#endif  // BLIMP_CLIENT_CORE_RENDER_WIDGET_BLIMP_DOCUMENT_H_