predictors: Add a origin for prefetch requests, remove the URL/host settings.

chrome/browser/predictors/resource_prefetch_common.h

 // 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 <stddef.h>
 
 #include "base/time/time.h"
@@ skipping 41 matching lines @@
   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.
+// Represents the config for the resource prefetch prediction algorithm.
 struct ResourcePrefetchPredictorConfig {
   // Initializes the config with default values.
   ResourcePrefetchPredictorConfig();
   ResourcePrefetchPredictorConfig(const ResourcePrefetchPredictorConfig& other);
   ~ResourcePrefetchPredictorConfig();
 
+  // Indicates what caused the prefetch request.
+  enum Origin { ORIGIN_NAVIGATION = 0, ORIGIN_EXTERNAL = 1 };

[pasko, 2016/11/29 14:44:44]

Please move it out of ResourcePrefetchPredictorConfig, the clients of this enum
do not have to know what the config is, right?

Reducing namespace pollution is still recommended with scoped enums, like:

enum class PrefetchOrigin {
  NAVIGATION,
  EXTERNAL
};

[Benoit L, 2016/11/29 17:02:51]

Done.

+
   // 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_PREFETCHING = 1 << 3  // Should also turn on HOST_LEARNING.
+    LEARNING = 1 << 0,
+    PREFETCHING_FOR_NAVIGATION = 1 << 2,  // Also enables LEARNING.
+    PREFETCHING_FOR_EXTERNAL = 1 << 3     // Also enables LEARNING.
   };
   int mode;
 
   // Helpers to deal with mode.
   bool IsLearningEnabled() const;
-  bool IsPrefetchingEnabled(Profile* profile) const;
-  bool IsURLLearningEnabled() const;
-  bool IsHostLearningEnabled() const;
-  bool IsURLPrefetchingEnabled(Profile* profile) const;
-  bool IsHostPrefetchingEnabled(Profile* profile) const;
+  bool IsAnyPrefetchingEnabled(Profile* profile) const;
+  bool IsPrefetchingEnabled(Profile* profile, Origin origin) const;

[pasko, 2016/11/29 14:44:44]

how about:

IsPrefetchingEnabledForOrigin(profile, origin),
IsPrefetchingEnabledForSomeOrigin(profile)

Otherwise the names did not clearly explain what the functions do (parameters
explain better, but I think my suggestion is even better)

Alternatively, remove the useless comment above the declaration of the 3
functions, and replace with more detailed comments for these including what they
do with |origin|.

[Benoit L, 2016/11/29 17:02:51]

Done.

 
   bool IsLowConfidenceForTest() const;
   bool IsHighConfidenceForTest() const;
   bool IsMoreResourcesEnabledForTest() const;
   bool IsSmallDBEnabledForTest() 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;
 
@@ skipping 20 matching lines @@
   // 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_