Add TabManager class, relocate Tab to common/.

blimp/engine/common/tab.h

Index: blimp/engine/common/tab.h
diff --git a/blimp/engine/common/tab.h b/blimp/engine/common/tab.h
new file mode 100644
index 0000000000000000000000000000000000000000..d18d3dd6f4769dbdb48bedbd948b46291cf6e331
--- /dev/null
+++ b/blimp/engine/common/tab.h
@@ -0,0 +1,40 @@
+// 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_ENGINE_COMMON_TAB_H_
+#define BLIMP_ENGINE_COMMON_TAB_H_
+
+#include <memory>
+
+#include "base/macros.h"
+
+namespace content {
+class WebContents;
+}
+
+namespace blimp {
+namespace engine {
+
+class PageLoadTracker;
+
+// Contains the state and metadata for a given tab.
+class Tab {
+ public:
+  Tab(int tab_id, std::unique_ptr<content::WebContents> web_contents);
+  ~Tab();
+
+  int id() const { return id_; }
+  content::WebContents* web_contents() const { return web_contents_.get(); }
+
+ private:
+  std::unique_ptr<content::WebContents> web_contents_;
+  const int id_;
+
+  DISALLOW_COPY_AND_ASSIGN(Tab);
+};
+
+}  // namespace engine
+}  // namespace blimp
+
+#endif  // BLIMP_ENGINE_COMMON_TAB_H_