Revert of PrerenderingLoader initial integration with PrerenderManager/PrerenderHandle

chrome/browser/android/offline_pages/prerendering_loader.h

Index: chrome/browser/android/offline_pages/prerendering_loader.h
diff --git a/chrome/browser/android/offline_pages/prerendering_loader.h b/chrome/browser/android/offline_pages/prerendering_loader.h
index 22659e96a3609d311ef21505beda494329244112..f4af6a2b7a2e0b37892acaf3ec965e59df8f1a2e 100644
--- a/chrome/browser/android/offline_pages/prerendering_loader.h
+++ b/chrome/browser/android/offline_pages/prerendering_loader.h
@@ -5,10 +5,7 @@
 #ifndef CHROME_BROWSER_ANDROID_OFFLINE_PAGES_PRERENDERING_LOADER_H_
 #define CHROME_BROWSER_ANDROID_OFFLINE_PAGES_PRERENDERING_LOADER_H_
 
-#include <memory>
-
 #include "base/callback.h"
-#include "chrome/browser/android/offline_pages/prerender_adapter.h"
 #include "components/offline_pages/background/offliner.h"
 
 class GURL;
@@ -26,99 +23,29 @@
 namespace offline_pages {
 
 // A client-side page loader that integrates with the PrerenderManager to do
-// the page loading in the background. It operates on a single thread and
-// needs to run on BrowserThread::UI to work with the PrerenderManager.
-// It supports a single load request at a time.
-class PrerenderingLoader : public PrerenderAdapter::Observer {
+// the page loading in the background.
+class PrerenderingLoader {
  public:
   // Reports status of a load page request with loaded contents if available.
-  typedef base::Callback<void(Offliner::RequestStatus, content::WebContents*)>
+  typedef base::Callback<void(Offliner::CompletionStatus,
+                              content::WebContents*)>
       LoadPageCallback;
 
   explicit PrerenderingLoader(content::BrowserContext* browser_context);
-  ~PrerenderingLoader() override;
+  virtual ~PrerenderingLoader();
 
   // Loads a page in the background if possible and returns whether the
   // request was accepted. If so, the LoadPageCallback will be informed
   // of status. Only one load request may exist as a time. If a previous
-  // request is still in progress it must be stopped before a new
-  // request will be accepted. The callback may be called more than
-  // once - first for a successful load and then if canceled after the
-  // load (which may be from resources being reclaimed) at which point
-  // the retrieved WebContents should no longer be used.
+  // request is still in progress it must be canceled before a new
+  // request will be accepted.
   virtual bool LoadPage(const GURL& url, const LoadPageCallback& callback);
 
   // Stops (completes or cancels) the load request. Must be called when
-  // LoadPageCallback is done with consuming the contents. May be called
-  // prior to LoadPageCallback in order to cancel the current request (in
-  // which case the callback will not be run).
+  // LoadPageCallback is done with consuming the contents.
   // This loader should also be responsible for stopping offline
   // prerenders when Chrome is transitioned to foreground.
   virtual void StopLoading();
-
-  // Returns whether prerendering is possible for this device's configuration
-  // and the browser context.
-  virtual bool CanPrerender();
-
-  // Returns whether the loader is idle and able to accept new LoadPage
-  // request.
-  virtual bool IsIdle();
-
-  // Returns whether the loader has successfully loaded web contents.
-  // Note that |StopLoading()| should be used to clear this state once
-  // the loaded web contents are no longer needed.
-  virtual bool IsLoaded();
-
-  // Overrides the prerender stack adapter for unit testing.
-  void SetAdapterForTesting(
-      std::unique_ptr<PrerenderAdapter> prerender_adapter);
-
-  // PrerenderAdapter::Observer implementation:
-  void OnPrerenderStart() override;
-  void OnPrerenderStopLoading() override;
-  void OnPrerenderDomContentLoaded() override;
-  void OnPrerenderStop() override;
-
- private:
-  // State of the loader (only one request may be active at a time).
-  enum class State {
-    IDLE,     // No active load request.
-    PENDING,  // Load request is pending the start of prerendering.
-    LOADING,  // Loading in progress.
-    LOADED,   // Loaded and now waiting for requestor to StopLoading().
-  };
-
-  // Handles some event/signal that the load request has succeeded or failed.
-  // It may be due to some asynchronous trigger that occurs after the request
-  // has completed for some other reason/event.
-  void HandleLoadEvent();
-
-  // Handles some event/signal that loading has stopped (whether due to a
-  // failure, cancel, or stop request). It may be due to some asynchronous
-  // trigger that occurs after the request has stopped for some other reason.
-  void HandleLoadingStopped();
-
-  // Cancels any current prerender and moves loader to idle state.
-  void CancelPrerender();
-
-  // Tracks loading state including whether the Loader is idle.
-  State state_;
-
-  // Not owned.
-  content::BrowserContext* browser_context_;
-
-  // Adapter for handling calls to the prerender stack.
-  std::unique_ptr<PrerenderAdapter> adapter_;
-
-  // A WebContents for the active load request that is used to hold the session
-  // storage namespace for rendering. This will NOT have the loaded page.
-  std::unique_ptr<content::WebContents> session_contents_;
-
-  // Callback to call when the active load request completes, fails, or is
-  // canceled.
-  LoadPageCallback callback_;
-
-  DISALLOW_COPY_AND_ASSIGN(PrerenderingLoader);
 };
 
 }  // namespace offline_pages