Revert of Revert CL 117933003. Re-add resource speculative prefetching code.

chrome/browser/predictors/resource_prefetch_common.h

Index: chrome/browser/predictors/resource_prefetch_common.h
diff --git a/chrome/browser/predictors/resource_prefetch_common.h b/chrome/browser/predictors/resource_prefetch_common.h
deleted file mode 100644
index f94a50dbe08918757dcb6889141c275a15076106..0000000000000000000000000000000000000000
--- a/chrome/browser/predictors/resource_prefetch_common.h
+++ /dev/null
@@ -1,116 +0,0 @@
-// Copyright 2014 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_PREFETCH_COMMON_H_
-#define CHROME_BROWSER_PREDICTORS_RESOURCE_PREFETCH_COMMON_H_
-
-#include "base/time/time.h"
-#include "url/gurl.h"
-
-class Profile;
-
-namespace content {
-class WebContents;
-}
-
-namespace predictors {
-
-struct ResourcePrefetchPredictorConfig;
-
-// Returns true if prefetching is enabled. And will initilize the |config|
-// fields to the appropritate values.
-bool IsSpeculativeResourcePrefetchingEnabled(
-    Profile* profile,
-    ResourcePrefetchPredictorConfig* config);
-
-// Represents the type of key based on which prefetch data is stored.
-enum PrefetchKeyType {
-  PREFETCH_KEY_TYPE_HOST,
-  PREFETCH_KEY_TYPE_URL
-};
-
-// Represents a single navigation for a render frame.
-struct NavigationID {
-  // TODO(shishir): Maybe take process_id, frame_id and url as input in
-  // constructor.
-  NavigationID();
-  NavigationID(const NavigationID& other);
-  explicit NavigationID(content::WebContents* web_contents);
-  bool operator<(const NavigationID& rhs) const;
-  bool operator==(const NavigationID& rhs) const;
-
-  bool IsSameRenderer(const NavigationID& other) const;
-
-  // Returns true iff the render_process_id_, render_frame_id_ and
-  // frame_url_ has been set correctly.
-  bool is_valid() const;
-
-  int render_process_id;
-  int render_frame_id;
-  GURL main_frame_url;
-
-  // NOTE: Even though we store the creation time here, it is not used during
-  // comparison of two NavigationIDs because it cannot always be determined
-  // correctly.
-  base::TimeTicks creation_time;
-};
-
-// Represents the config for the resource prefetch prediction algorithm. It is
-// useful for running experiments.
-struct ResourcePrefetchPredictorConfig {
-  // Initializes the config with default values.
-  ResourcePrefetchPredictorConfig();
-  ~ResourcePrefetchPredictorConfig();
-
-  // The mode the prefetcher is running in. Forms a bit map.
-  enum Mode {
-    URL_LEARNING    = 1 << 0,
-    HOST_LEARNING   = 1 << 1,
-    URL_PREFETCHING = 1 << 2,  // Should also turn on URL_LEARNING.
-    HOST_PRFETCHING = 1 << 3   // Should also turn on HOST_LEARNING.
-  };
-  int mode;
-
-  // Helpers to deal with mode.
-  bool IsLearningEnabled() const;
-  bool IsPrefetchingEnabled() const;
-  bool IsURLLearningEnabled() const;
-  bool IsHostLearningEnabled() const;
-  bool IsURLPrefetchingEnabled() const;
-  bool IsHostPrefetchingEnabled() const;
-
-  // If a navigation hasn't seen a load complete event in this much time, it
-  // is considered abandoned.
-  size_t max_navigation_lifetime_seconds;
-
-  // Size of LRU caches for the URL and host data.
-  size_t max_urls_to_track;
-  size_t max_hosts_to_track;
-
-  // The number of times we should have seen a visit to this URL in history
-  // to start tracking it. This is to ensure we don't bother with oneoff
-  // entries. For hosts we track each one.
-  size_t min_url_visit_count;
-
-  // The maximum number of resources to store per entry.
-  size_t max_resources_per_entry;
-  // The number of consecutive misses after we stop tracking a resource URL.
-  size_t max_consecutive_misses;
-
-  // The minimum confidence (accuracy of hits) required for a resource to be
-  // prefetched.
-  float min_resource_confidence_to_trigger_prefetch;
-  // The minimum number of times we must have a URL on record to prefetch it.
-  size_t min_resource_hits_to_trigger_prefetch;
-
-  // Maximum number of prefetches that can be inflight for a single navigation.
-  size_t max_prefetches_inflight_per_navigation;
-  // Maximum number of prefetches that can be inflight for a host for a single
-  // navigation.
-  size_t max_prefetches_inflight_per_host_per_navigation;
-};
-
-}  // namespace predictors
-
-#endif  // CHROME_BROWSER_PREDICTORS_RESOURCE_PREFETCH_COMMON_H_