[Blimp] Creates engine tab class to handle tab related operations.

blimp/engine/session/tab_blimp.h

+// 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_SESSION_TAB_BLIMP_H_
+#define BLIMP_ENGINE_SESSION_TAB_BLIMP_H_
+
+#include "base/macros.h"
+#include "content/public/browser/invalidate_type.h"
+#include "content/public/browser/web_contents_observer.h"
+#include "blimp/engine/session/page_load_tracker.h"
+
+namespace content {
+class RenderViewHost;
+class WebContents;
+}
+
+namespace blimp {
+class BlimpMessageProcessor;
+
+namespace engine {
+class EngineRenderWidgetFeature;
+
+// Owns WebContents, handles operations in the tab, and has one-to-one mapping
+// to a client tab.
+class TabBlimp : public content::WebContentsObserver,
+                 public PageLoadTrackerClient {
+ public:
+  // Caller ensures |render_widget_feature| and |navigation_message_sender|

[Kevin M, 2016/06/02 21:54:05]

Document ctor parameters.

[haibinlu, 2016/06/02 23:24:33]

Done.

+  // outlives this object.
+  explicit TabBlimp(std::unique_ptr<content::WebContents> web_contents,
+                    const int tab_id,
+                    EngineRenderWidgetFeature* render_widget_feature,
+                    BlimpMessageProcessor* navigation_message_sender);
+  ~TabBlimp() override;
+
+  content::WebContents* web_contents() { return web_contents_.get(); }
+  int tab_id() const { return tab_id_; }
+
+  void Resize(float device_pixel_ratio, const gfx::Size& size_in_dips);
+  void LoadUrl(const GURL& url);
+  void GoBack();
+  void GoForward();
+  void Reload();
+  void NavigationStateChanged(content::InvalidateTypes changed_flags);
+
+  // PageLoadTrackerClient implementation.
+  void SendPageLoadStatusUpdate(PageLoadStatus load_status) override;
+
+ private:
+  // content::WebContentsObserver implementation.
+  void RenderViewCreated(content::RenderViewHost* render_view_host) override;
+  void RenderViewHostChanged(content::RenderViewHost* old_host,
+                             content::RenderViewHost* new_host) override;
+  void RenderViewDeleted(content::RenderViewHost* render_view_host) override;
+
+  std::unique_ptr<content::WebContents> web_contents_;
+  const int tab_id_;
+  EngineRenderWidgetFeature* render_widget_feature_;
+  BlimpMessageProcessor* navigation_message_sender_;
+
+  // Tracks the page load status for a tab. Each PageLoadTracker is tied to a

[Kevin M, 2016/06/02 21:54:05]

What does "tied to" mean in this case? Must be deleted before a WebContents?

The second part of this comment isn't really relevant - this is implied by the
Tab object owning both the tracker and the WebContents.

[haibinlu, 2016/06/02 23:24:33]

Updated comments. page_load_tracker_ takes webcontents as parameter. thus it is
constructed after.

+  // WebContents.
+  std::unique_ptr<PageLoadTracker> page_load_tracker_;
+
+  DISALLOW_COPY_AND_ASSIGN(TabBlimp);
+};
+
+}  // namespace engine
+}  // namespace blimp
+
+#endif  // BLIMP_ENGINE_SESSION_TAB_BLIMP_H_