Adds speculative prefetching of resources.

chrome/browser/predictors/resource_prefetcher_manager.h

+// Copyright (c) 2012 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 CHROME_BROWSER_PREDICTORS_RESOURCE_PREFETCHER_MANAGER_H_
+#define CHROME_BROWSER_PREDICTORS_RESOURCE_PREFETCHER_MANAGER_H_
+
+#include <map>
+
+#include "base/memory/linked_ptr.h"
+#include "base/memory/ref_counted.h"
+#include "chrome/browser/predictors/resource_prefetcher.h"
+#include "chrome/browser/predictors/resource_prefetch_common.h"
+
+namespace net {
+class URLRequestContextGetter;
+}
+
+namespace predictors {
+
+struct NavigationID;
+
+// Manages prefetches for multple navigations.
+//  - Created and owned by the resource prefetch predictor.
+//  - Created on the UI thread, but most functions are called in the IO thread.
+//  - Will only allow one inflight prefresh per main frame URL.
+class ResourcePrefetcherManager
+      : public ResourcePrefetcher::Delegate,
+        public base::RefCountedThreadSafe<ResourcePrefetcherManager> {

[dominich, 2012/07/23 16:04:41]

If this is created and owned by the resource prefetch predictor, which is
profile keyed, why does this need to be refcounted?

[Shishir, 2012/08/01 22:35:24]

Because this needs to be de-referenced on two different threads. The UI thread
to interact with the predictor and the IO thread to interact with the
prefetchers.

+ public:
+  // Used to notify when prefetching is done for a single navigation.
+  // The Delegate will be called on the UI Thread and should be alive till
+  // ShutdownOnUIThread is called.
+  // manager.

[dominich, 2012/07/23 16:04:41]

nit: extra word.

[Shishir, 2012/08/01 22:35:24]

Done.

+  class Delegate {

[dominich, 2012/07/23 16:04:41]

I think this is such a tightly bound system that using Delegates is pointless
and reduces readability.

[Shishir, 2012/08/01 22:35:24]

Removed.

+   public:
+    virtual ~Delegate() { }
+    virtual void FinishedPrefetchForNavigation(
+        const NavigationID& navigation_id,
+        scoped_ptr<ResourcePrefetcher::RequestVector> requests) = 0;
+  };
+
+  ResourcePrefetcherManager(Delegate* delegate,
+                            const ResourcePrefetchPredictorConfig& config,
+                            net::URLRequestContextGetter* getter);
+
+  // UI thread.
+  void ShutdownOnUIThread();
+
+  // --- IO Thread methods.
+
+  // The prefetchers need to be deleted on the IO thread.
+  void ShutdownOnIOThread();
+
+  // Will create a new ResourcePrefetcher for the main frame url of the input
+  // navigation if there isn't one already for the same URL.
+  void MaybeAddPrefetch(const NavigationID& navigation_id,
+                        scoped_ptr<ResourcePrefetcher::RequestVector> requests);
+
+  // Stops the ResourcePrefetcher for the input navigation, if one was in
+  // progress.
+  void MaybeRemovePrefetch(const NavigationID& navigation_id);
+
+ private:
+  friend class base::RefCountedThreadSafe<ResourcePrefetcherManager>;
+
+  virtual ~ResourcePrefetcherManager();
+
+  // ResourcePrefetcher::Delegate methods OVERRIDE.
+  virtual void ResourcePrefetcherFinished(
+      ResourcePrefetcher* prefetcher,
+      scoped_ptr<ResourcePrefetcher::RequestVector> requests) OVERRIDE;
+  virtual net::URLRequestContext* GetURLRequestContext() OVERRIDE;
+
+  // UI Thread.
+  // The delegate needs to be called on the UI thread.
+  void ResourcePrefetcherFinishedOnUI(
+      const NavigationID& navigation_id,
+      scoped_ptr<ResourcePrefetcher::RequestVector> requests);
+
+  Delegate* delegate_;  // Can only be called on the UI thread.
+  ResourcePrefetchPredictorConfig config_;
+  net::URLRequestContextGetter* context_getter_;
+  std::map<GURL, linked_ptr<ResourcePrefetcher> > prefetchers_;
+
+  DISALLOW_COPY_AND_ASSIGN(ResourcePrefetcherManager);
+};
+
+}  // namespace predictors
+
+#endif  // CHROME_BROWSER_PREDICTORS_RESOURCE_PREFETCHER_MANAGER_H_