predictors: Disable URL-based learning by default.

chrome/browser/predictors/resource_prefetch_common.cc

Index: chrome/browser/predictors/resource_prefetch_common.cc
diff --git a/chrome/browser/predictors/resource_prefetch_common.cc b/chrome/browser/predictors/resource_prefetch_common.cc
index 27ea7933c98834c5ddcc57903fc9775dce60cd82..ccd3139e4d30b17fe8b225ec9201a3960270747e 100644
--- a/chrome/browser/predictors/resource_prefetch_common.cc
+++ b/chrome/browser/predictors/resource_prefetch_common.cc
@@ -7,14 +7,12 @@
 #include <string>
 #include <tuple>
 
-#include "base/command_line.h"
-#include "base/metrics/field_trial.h"
+#include "base/feature_list.h"
+#include "base/metrics/field_trial_params.h"
 #include "chrome/browser/net/prediction_options.h"
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/browser/sessions/session_tab_helper.h"
-#include "chrome/common/chrome_switches.h"
 #include "components/prefs/pref_service.h"
-#include "components/variations/variations_associated_data.h"
 #include "content/public/browser/browser_thread.h"
 #include "content/public/browser/web_contents.h"
 
@@ -26,6 +24,10 @@ const char kModeParamName[] = "mode";
 const char kLearningMode[] = "learning";
 const char kExternalPrefetchingMode[] = "external-prefetching";
 const char kPrefetchingMode[] = "prefetching";
+const char kKeyTypeParamName[] = "key-type";
+const char kUrlKeyType[] = "url";
+const char kHostKeyType[] = "host";
+const char kBothKeyType[] = "both";
 
 namespace {
 
@@ -61,18 +63,29 @@ bool IsSpeculativeResourcePrefetchingEnabled(
   if (!base::FeatureList::IsEnabled(kSpeculativeResourcePrefetchingFeature))
     return false;
 
-  std::string mode_value = variations::GetVariationParamValueByFeature(
+  std::string key_type_value = base::GetFieldTrialParamValueByFeature(

[Benoit L, 2017/03/01 16:04:41]

Do we really want URL-only?

If not, can we simplify the code (and the settings). We then just need something
to force host and url, since the default is host only.

[alexilin, 2017/03/01 16:55:56]

Done.

+      kSpeculativeResourcePrefetchingFeature, kKeyTypeParamName);
+  if (key_type_value == kUrlKeyType) {
+    config->mode |= ResourcePrefetchPredictorConfig::URL_LEARNING;
+  } else if (key_type_value == kHostKeyType) {
+    config->mode |= ResourcePrefetchPredictorConfig::HOST_LEARNING;
+  } else if (key_type_value == kBothKeyType) {
+    config->mode |= ResourcePrefetchPredictorConfig::URL_LEARNING |
+                    ResourcePrefetchPredictorConfig::HOST_LEARNING;
+  } else {
+    // Only host learning by default.
+    config->mode |= ResourcePrefetchPredictorConfig::HOST_LEARNING;
+  }
+
+  std::string mode_value = base::GetFieldTrialParamValueByFeature(
       kSpeculativeResourcePrefetchingFeature, kModeParamName);
   if (mode_value == kLearningMode) {
-    config->mode |= ResourcePrefetchPredictorConfig::LEARNING;
     return true;
   } else if (mode_value == kExternalPrefetchingMode) {
-    config->mode |= ResourcePrefetchPredictorConfig::LEARNING |
-                    ResourcePrefetchPredictorConfig::PREFETCHING_FOR_EXTERNAL;
+    config->mode |= ResourcePrefetchPredictorConfig::PREFETCHING_FOR_EXTERNAL;
     return true;
   } else if (mode_value == kPrefetchingMode) {
-    config->mode |= ResourcePrefetchPredictorConfig::LEARNING |
-                    ResourcePrefetchPredictorConfig::PREFETCHING_FOR_EXTERNAL |
+    config->mode |= ResourcePrefetchPredictorConfig::PREFETCHING_FOR_EXTERNAL |
                     ResourcePrefetchPredictorConfig::PREFETCHING_FOR_NAVIGATION;
     return true;
   }
@@ -135,7 +148,15 @@ ResourcePrefetchPredictorConfig::~ResourcePrefetchPredictorConfig() {
 }
 
 bool ResourcePrefetchPredictorConfig::IsLearningEnabled() const {
-  return (mode & LEARNING) > 0;
+  return IsURLLearningEnabled() || IsHostLearningEnabled();
+}
+
+bool ResourcePrefetchPredictorConfig::IsURLLearningEnabled() const {
+  return (mode & URL_LEARNING) > 0;
+}
+
+bool ResourcePrefetchPredictorConfig::IsHostLearningEnabled() const {
+  return (mode & HOST_LEARNING) > 0;
 }
 
 bool ResourcePrefetchPredictorConfig::IsPrefetchingEnabledForSomeOrigin(