third_party/WebKit/Source/core/dom/ContextFeaturesClientImpl.cpp

/*
 * Copyright (C) 2012 Google Inc. All rights reserved.
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#include "core/dom/ContextFeaturesClientImpl.h"

#include "core/dom/Document.h"
#include "core/frame/ContentSettingsClient.h"
#include "platform/weborigin/SecurityOrigin.h"

namespace blink {

class ContextFeaturesCache final
    : public GarbageCollectedFinalized<ContextFeaturesCache>,
      public Supplement<Document> {
  USING_GARBAGE_COLLECTED_MIXIN(ContextFeaturesCache);

 public:
  class Entry {
   public:
    enum Value { kIsEnabled, kIsDisabled, kNeedsRefresh };

    Entry() : value_(kNeedsRefresh), default_value_(false) {}

    bool IsEnabled() const {
      DCHECK_NE(value_, kNeedsRefresh);
      return value_ == kIsEnabled;
    }

    void Set(bool value, bool default_value) {
      value_ = value ? kIsEnabled : kIsDisabled;
      default_value_ = default_value;
    }

    bool NeedsRefresh(bool default_value) const {
      return value_ == kNeedsRefresh || default_value_ != default_value;
    }

   private:
    Value value_;
    bool default_value_;  // Needs to be traked as a part of the signature since
                          // it can be changed dynamically.
  };

  static const char* SupplementName();
  static ContextFeaturesCache& From(Document&);

  Entry& EntryFor(ContextFeatures::FeatureType type) {
    size_t index = static_cast<size_t>(type);
    SECURITY_DCHECK(index < ContextFeatures::kFeatureTypeSize);
    return entries_[index];
  }

  void ValidateAgainst(Document*);

  virtual void Trace(blink::Visitor* visitor) {
    Supplement<Document>::Trace(visitor);
  }

 private:
  explicit ContextFeaturesCache(Document& document)
      : Supplement<Document>(document) {}

  String domain_;
  Entry entries_[ContextFeatures::kFeatureTypeSize];
};

const char* ContextFeaturesCache::SupplementName() {
  return "ContextFeaturesCache";
}

ContextFeaturesCache& ContextFeaturesCache::From(Document& document) {
  ContextFeaturesCache* cache = static_cast<ContextFeaturesCache*>(
      Supplement<Document>::From(document, SupplementName()));
  if (!cache) {
    cache = new ContextFeaturesCache(document);
    Supplement<Document>::ProvideTo(document, SupplementName(), cache);
  }

  return *cache;
}

void ContextFeaturesCache::ValidateAgainst(Document* document) {
  String current_domain = document->GetSecurityOrigin()->Domain();
  if (current_domain == domain_)
    return;
  domain_ = current_domain;
  for (size_t i = 0; i < ContextFeatures::kFeatureTypeSize; ++i)
    entries_[i] = Entry();
}

bool ContextFeaturesClientImpl::IsEnabled(Document* document,
                                          ContextFeatures::FeatureType type,
                                          bool default_value) {
  DCHECK(document);
  ContextFeaturesCache::Entry& cache =
      ContextFeaturesCache::From(*document).EntryFor(type);
  if (cache.NeedsRefresh(default_value))
    cache.Set(AskIfIsEnabled(document, type, default_value), default_value);
  return cache.IsEnabled();
}

void ContextFeaturesClientImpl::UrlDidChange(Document* document) {
  DCHECK(document);
  ContextFeaturesCache::From(*document).ValidateAgainst(document);
}

bool ContextFeaturesClientImpl::AskIfIsEnabled(
    Document* document,
    ContextFeatures::FeatureType type,
    bool default_value) {
  LocalFrame* frame = document->GetFrame();
  if (!frame || !frame->GetContentSettingsClient())
    return default_value;

  switch (type) {
    case ContextFeatures::kMutationEvents:
      return frame->GetContentSettingsClient()->AllowMutationEvents(
          default_value);
    default:
      return default_value;
  }
}

}  // namespace blink