Remove all blimp engine code

blimp/engine/session/page_load_tracker.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_PAGE_LOAD_TRACKER_H_
-#define BLIMP_ENGINE_SESSION_PAGE_LOAD_TRACKER_H_
-
-#include "base/cancelable_callback.h"
-#include "base/macros.h"
-#include "content/public/browser/render_frame_host.h"
-#include "content/public/browser/render_widget_host.h"
-#include "content/public/browser/web_contents_observer.h"
-
-namespace blimp {
-namespace engine {
-
-enum class PageLoadStatus { LOADING, LOADED };
-
-class PageLoadTrackerClient {
- public:
-  virtual ~PageLoadTrackerClient() {}
-
-  // Called when a navigation status update should be sent to the client.
-  // |load_status| indicates the status of the navigation. An update with a
-  // |LOADING| value is sent each time a new navigation is initiated. This
-  // update will be followed by a |LOADED| value when the navigation either
-  // successfully finishes or fails.
-  virtual void SendPageLoadStatusUpdate(PageLoadStatus load_status) = 0;
-};
-
-// Tracks the page load status for a tab using load and paint notifications
-// from the renderer.
-class PageLoadTracker : public content::WebContentsObserver {
- public:
-  explicit PageLoadTracker(content::WebContents* web_contents,
-                           PageLoadTrackerClient* client);
-  ~PageLoadTracker() override;
-
- private:
-  // content::WebContentsObserver implementation.
-  void DidStartNavigation(
-      content::NavigationHandle* navigation_handle) override;
-  void DidFinishNavigation(
-      content::NavigationHandle* navigation_handle) override;
-
-  // Invoked when the renderer has performed at least one paint after the
-  // navigation was committed.
-  void DidPaintAfterNavigationCommitted(bool result);
-
-  base::CancelableCallback<void(bool)> did_paint_after_navigation_callback_;
-
-  PageLoadTrackerClient* client_;
-
-  DISALLOW_COPY_AND_ASSIGN(PageLoadTracker);
-};
-
-}  // namespace engine
-}  // namespace blimp
-
-#endif  // BLIMP_ENGINE_SESSION_PAGE_LOAD_TRACKER_H_