Remove legacy support for top-level hint optimizations

Clients, starting at M-72, no longer support top-level hint
optimizations for the existing optimization types, so the code
supporting them is being removed.

The server may add new top-level optimization types in the future,
so the proto field is not being deprecated.

Bug: 917189

Change-Id: Ib6a1bb96958ff96dfd65921d9afd4b8bac8bf39c
Reviewed-on: https://chromium-review.googlesource.com/c/1387950
Commit-Queue: Jered Gray <jegray@chromium.org>
Reviewed-by: Tarun Bansal <tbansal@chromium.org>
Reviewed-by: Doug Arnett <dougarnett@chromium.org>
Cr-Commit-Position: refs/heads/master@{#618585}

components/optimization_guide/proto/hints.proto

@@ -133,12 +133,8 @@ message Hint {
   // The key that applies to this hint. The key_representation field describes
   // the form in which this key takes. Guaranteed to be non-empty.
   optional string key = 2;
-  // An unordered set of optimizations that should be whitelisted for this
-  // hint.
-  // If empty, then no optimizations should be whitelisted (this allows for an
-  // earlier hint entry to act as an exception to a subsequently matching hint
-  // whitelist entry). If multiple optimizations or page_hints are provided, the
-  // client will decide which one to act on.
+  // Top-level optimizations are currently unused on the client as of M-72. This
+  // may change in the future as new optimization types are added.
   repeated Optimization whitelisted_optimizations = 3;
   // An ordered set of per-page hints. Only the first PageHint record
   // that matches a committed page URL should be used for that page load.

components/previews/content/previews_hints.cc

@@ -315,13 +315,6 @@ std::unique_ptr<PreviewsHints> PreviewsHints::CreateFromHintsComponent(
   std::unique_ptr<PreviewsHints> hints(new PreviewsHints());
   HintCache::Data hint_cache_data;
 
-  // The condition set ID is a simple increasing counter that matches the
-  // order of hints in the config (where earlier hints in the config take
-  // precedence over later hints in the config if there are multiple matches).
-  url_matcher::URLMatcherConditionSet::ID id = 0;
-  url_matcher::URLMatcherConditionFactory* condition_factory =
-      hints->url_matcher_.condition_factory();
-  url_matcher::URLMatcherConditionSet::Vector all_conditions;
   std::set<std::string> seen_host_suffixes;
 
   size_t total_page_patterns_with_resource_loading_hints_received = 0;
@@ -350,38 +343,6 @@ std::unique_ptr<PreviewsHints> PreviewsHints::CreateFromHintsComponent(
     }
     seen_host_suffixes.insert(hint_key);
 
-    // Only process legacy top level hints if specifically enabled.
-    if (previews::params::NoScriptPreviewsUsesTopLevelHints()) {
-      // Create whitelist condition set out of the optimizations that are
-      // whitelisted for the host suffix at the top level (i.e., not within
-      // PageHints).
-      std::set<std::pair<PreviewsType, int>> whitelisted_optimizations;
-      for (const auto& optimization : hint.whitelisted_optimizations()) {
-        if (IsDisabledExperimentalOptimization(optimization)) {
-          continue;
-        }
-        base::Optional<PreviewsType> previews_type =
-            ConvertProtoOptimizationTypeToPreviewsType(
-                optimization.optimization_type());
-        if (!previews_type.has_value()) {
-          continue;
-        }
-        // Resource loading hints should always be page hints; if they appear as
-        // top-level whitelisted optimizations, then it indicates a bug.
-        DCHECK(previews_type != PreviewsType::RESOURCE_LOADING_HINTS);
-
-        whitelisted_optimizations.insert(std::make_pair(
-            previews_type.value(), optimization.inflation_percent()));
-      }
-
-      url_matcher::URLMatcherCondition condition =
-          condition_factory->CreateHostSuffixCondition(hint_key);
-      all_conditions.push_back(new url_matcher::URLMatcherConditionSet(
-          id, std::set<url_matcher::URLMatcherCondition>{condition}));
-      hints->whitelist_[id] = whitelisted_optimizations;
-      id++;
-    }
-
     // If this hint contains page hints, then add a pared down version of the
     // hint to the initial hints that are used to populate the hint cache,
     // removing all of the hint's top-level optimizations and only retaining the
@@ -401,10 +362,6 @@ std::unique_ptr<PreviewsHints> PreviewsHints::CreateFromHintsComponent(
         total_resource_loading_hints_received);
   }
 
-  if (!all_conditions.empty()) {
-    hints->url_matcher_.AddConditionSets(all_conditions);
-  }
-
   if (hint_cache_data.HasHints()) {
     hints->hint_cache_ =
         std::make_unique<HintCache>(std::move(hint_cache_data));
@@ -416,7 +373,7 @@ std::unique_ptr<PreviewsHints> PreviewsHints::CreateFromHintsComponent(
   // Completed processing hints data without crashing so clear sentinel.
   DeleteSentinelFile(sentinel_path);
   RecordProcessHintsResult(
-      all_conditions.empty() && !hints->hint_cache_
+      !hints->hint_cache_
           ? PreviewsProcessHintsResult::kProcessedNoPreviewsHints
           : PreviewsProcessHintsResult::kProcessedPreviewsHints);
   return hints;
@@ -507,64 +464,11 @@ bool PreviewsHints::IsWhitelisted(
     net::EffectiveConnectionType* out_ect_threshold) const {
   DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
 
-  if (!url.has_host()) {
-    return false;
-  }
-
-  return IsWhitelistedAtTopLevel(url, type, out_inflation_percent) ||
-         IsWhitelistedInPageHints(url, type, out_inflation_percent,
-                                  out_ect_threshold);
-}
-
-bool PreviewsHints::IsWhitelistedAtTopLevel(const GURL& url,
-                                            PreviewsType type,
-                                            int* out_inflation_percent) const {
-  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
-
-  // Top level hints are deprecated so only check here if specifically enabled
-  // for NoScript.
-  if (!previews::params::NoScriptPreviewsUsesTopLevelHints()) {
-    return false;
-  }
-
-  // Resource loading hints are not processed in the top-level whitelist.
-  if (type == PreviewsType::RESOURCE_LOADING_HINTS) {
+  if (!hint_cache_) {
     return false;
   }
 
-  std::set<url_matcher::URLMatcherConditionSet::ID> matches =
-      url_matcher_.MatchURL(url);
-
-  // Only consider the first match in iteration order as it takes precedence
-  // if there are multiple matches for the top-level whitelist.
-  const auto& first_match = matches.begin();
-  if (first_match != matches.end()) {
-    const auto whitelist_iter = whitelist_.find(*first_match);
-    if (whitelist_iter != whitelist_.end()) {
-      const auto& whitelisted_optimizations = whitelist_iter->second;
-      for (auto optimization_iter = whitelisted_optimizations.begin();
-           optimization_iter != whitelisted_optimizations.end();
-           ++optimization_iter) {
-        if (optimization_iter->first == type) {
-          *out_inflation_percent = optimization_iter->second;
-          // Whitelisted on top level whitelist.
-          return true;
-        }
-      }
-    }
-  }
-
-  return false;
-}
-
-bool PreviewsHints::IsWhitelistedInPageHints(
-    const GURL& url,
-    PreviewsType type,
-    int* out_inflation_percent,
-    net::EffectiveConnectionType* out_ect_threshold) const {
-  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
-
-  if (!hint_cache_) {
+  if (!url.has_host()) {
     return false;
   }
 

components/previews/content/previews_hints.h

@@ -5,7 +5,6 @@
 #ifndef COMPONENTS_PREVIEWS_CONTENT_PREVIEWS_HINTS_H_
 #define COMPONENTS_PREVIEWS_CONTENT_PREVIEWS_HINTS_H_
 
-#include <map>
 #include <memory>
 #include <set>
 #include <utility>
@@ -18,7 +17,6 @@
 #include "components/previews/content/previews_hints.h"
 #include "components/previews/content/previews_user_data.h"
 #include "components/previews/core/host_filter.h"
-#include "components/url_matcher/url_matcher.h"
 #include "net/nqe/effective_connection_type.h"
 
 class GURL;
@@ -48,9 +46,7 @@ class PreviewsHints {
 
   // Whether the URL is whitelisted for the given previews type. If so,
   // |out_inflation_percent| and |out_ect_threshold| will be populated if
-  // metadata is available for them. This first checks the top-level whitelist
-  // and, if not whitelisted there, it will check the HintCache for having a
-  // loaded, matching PageHint that whitelists it.
+  // metadata is available for them.
   bool IsWhitelisted(const GURL& url,
                      PreviewsType type,
                      int* out_inflation_percent,
@@ -83,40 +79,14 @@ class PreviewsHints {
 
   PreviewsHints();
 
-  // Returns whether |url| is whitelisted in |whitelist_|. If it is, then
-  // |out_inflation_percent| will be populated if metadata is available for it.
-  // NOTE: PreviewsType::RESOURCE_LOADING_HINTS cannot be whitelisted at the
-  // top-level.
-  bool IsWhitelistedAtTopLevel(const GURL& url,
-                               PreviewsType type,
-                               int* out_inflation_percent) const;
-  // Returns whether |url| is whitelisted in the page hints contained within
-  // |hint_cache_|. If it is, then |out_inflation_percent| and
-  // |out_ect_threshold| will be populated if metadata is available for them.
-  bool IsWhitelistedInPageHints(
-      const GURL& url,
-      PreviewsType type,
-      int* out_inflation_percent,
-      net::EffectiveConnectionType* out_ect_threshold) const;
-
   // Parses optimization filters from |config| and populates corresponding
   // supported blacklists in this object.
   void ParseOptimizationFilters(
       const optimization_guide::proto::Configuration& config);
 
-  // The URLMatcher used to match whether a URL has any hints associated with
-  // it.
-  url_matcher::URLMatcher url_matcher_;
-
   // Holds the hint cache (if any optimizations using it are enabled).
   std::unique_ptr<HintCache> hint_cache_;
 
-  // A map from the condition set ID to associated whitelist Optimization
-  // details.
-  std::map<url_matcher::URLMatcherConditionSet::ID,
-           std::set<std::pair<PreviewsType, int>>>
-      whitelist_;
-
   // Blacklist of host suffixes for LITE_PAGE_REDIRECT Previews.
   std::unique_ptr<HostFilter> lite_page_redirect_blacklist_;
 

components/previews/core/previews_experiments.cc

@@ -335,11 +335,6 @@ int NoScriptPreviewsInflationBytes() {
                                           kNoScriptInflationBytes, 0);
 }
 
-bool NoScriptPreviewsUsesTopLevelHints() {
-  return base::FeatureList::IsEnabled(
-      features::kNoScriptPreviewsUsesTopLevelHints);
-}
-
 int ResourceLoadingHintsPreviewsInflationPercent() {
   return GetFieldTrialParamByFeatureAsInt(features::kResourceLoadingHints,
                                           kResourceLoadingHintsInflationPercent,

components/previews/core/previews_experiments.h

@@ -171,11 +171,6 @@ int NoScriptPreviewsInflationPercent();
 // for inflating the original_bytes count.
 int NoScriptPreviewsInflationBytes();
 
-// Whether to use top level optimization hints for NoScript instead of
-// page hints. This is to allow for reverting to original behavior until
-// page hints for NoScript is successfully launched.
-bool NoScriptPreviewsUsesTopLevelHints();
-
 // For estimating ResourceLoadingHints data savings, this is the percentage
 // factor to multiple by the network bytes for inflating the original_bytes
 // count.

components/previews/core/previews_features.cc

@@ -46,10 +46,6 @@ const base::Feature kNoScriptPreviews {
 #endif  // defined(OS_ANDROID)
 };
 
-// Enables using (legacy) top level optimization hints to whitelist NoScript.
-const base::Feature kNoScriptPreviewsUsesTopLevelHints{
-    "NoScriptPreviewsUsesTopLevelHints", base::FEATURE_DISABLED_BY_DEFAULT};
-
 // Enables the Stale Previews timestamp on Previews infobars.
 const base::Feature kStalePreviewsTimestamp{"StalePreviewsTimestamp",
                                             base::FEATURE_ENABLED_BY_DEFAULT};

components/previews/core/previews_features.h

@@ -14,7 +14,6 @@ extern const base::Feature kPreviews;
 extern const base::Feature kOfflinePreviews;
 extern const base::Feature kClientLoFi;
 extern const base::Feature kNoScriptPreviews;
-extern const base::Feature kNoScriptPreviewsUsesTopLevelHints;
 extern const base::Feature kStalePreviewsTimestamp;
 extern const base::Feature kOptimizationHints;
 extern const base::Feature kOptimizationHintsExperiments;