Abstract WebContents/NavigationController from core TabRestore code

components/sessions/core/live_tab.h

Index: components/sessions/core/live_tab.h
diff --git a/components/sessions/core/live_tab.h b/components/sessions/core/live_tab.h
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+// Copyright 2015 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 COMPONENTS_SESSIONS_CORE_LIVE_TAB_H_
+#define COMPONENTS_SESSIONS_CORE_LIVE_TAB_H_
+
+#include "base/basictypes.h"
+#include "components/sessions/serialized_navigation_entry.h"
+#include "components/sessions/sessions_export.h"
+
+namespace sessions {
+
+// Interface that represents a currently-live tab to the core sessions code, and
+// in particular, the tab restore service. This interface abstracts the concrete
+// representation of a live tab on different platforms (e.g., WebContents on
+// //content-based platforms).
+class SESSIONS_EXPORT LiveTab {
+ public:
+  virtual ~LiveTab() {}
+
+  // Methods that return information about the navigation state of the tab.
+  virtual int GetCurrentEntryIndex() = 0;
+  virtual int GetPendingEntryIndex() = 0;
+  virtual sessions::SerializedNavigationEntry GetEntryAtIndex(int index) = 0;
+  virtual sessions::SerializedNavigationEntry GetPendingEntry() = 0;
+  virtual int GetEntryCount() = 0;
+
+  // Loads the current page if necessary (where "necessary" is defined on a
+  // platform-specific basis).
+  virtual void LoadIfNecessary() = 0;
+
+  // Returns the user agent override, if any.
+  virtual const std::string& GetUserAgentOverride() const = 0;
+};
+
+}  // namespace sessions
+
+#endif  // COMPONENTS_SESSIONS_CORE_LIVE_TAB_H_