Add a feature which, when enabled, blocks permissions after X prompt dismissals.

chrome/browser/permissions/permission_prompt_decision_log.cc

+// Copyright 2016 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.
+
+#include "chrome/browser/permissions/permission_prompt_decision_log.h"
+
+#include <memory>
+
+#include "base/feature_list.h"
+#include "base/logging.h"
+#include "base/memory/ptr_util.h"
+#include "base/strings/string_number_conversions.h"
+#include "base/values.h"
+#include "chrome/browser/content_settings/host_content_settings_map_factory.h"
+#include "chrome/browser/permissions/permission_util.h"
+#include "chrome/common/chrome_features.h"
+#include "components/content_settings/core/browser/host_content_settings_map.h"
+#include "components/variations/variations_associated_data.h"
+#include "content/public/browser/permission_type.h"
+#include "url/gurl.h"
+
+namespace {
+
+// The default number of times that users may explicitly dismiss a permission
+// prompt from an origin before it is automatically blocked.
+int kPromptDismissalsBeforeBlock = 3;
+
+const char kPromptStudyName[] = "PermissionPromptsUX";
+const char kPromptDismissCountKey[] = "dismiss_count";
+
+std::unique_ptr<base::DictionaryValue> GetOriginDict(
+    HostContentSettingsMap* settings,
+    const GURL& origin_url) {
+  std::unique_ptr<base::DictionaryValue> dict =
+      base::DictionaryValue::From(settings->GetWebsiteSetting(
+          origin_url, origin_url,
+          CONTENT_SETTINGS_TYPE_PROMPT_NO_DECISION_COUNT, std::string(),
+          nullptr));
+  if (!dict)
+    return base::WrapUnique(new base::DictionaryValue());
+
+  return dict;
+}
+
+base::DictionaryValue* GetOrCreatePermissionDict(
+    base::DictionaryValue* origin_dict,
+    const std::string& permission) {
+  base::DictionaryValue* permission_dict = nullptr;
+  if (!origin_dict->GetDictionaryWithoutPathExpansion(permission,
+                                                      &permission_dict)) {
+    permission_dict = new base::DictionaryValue();
+    origin_dict->SetWithoutPathExpansion(permission,
+                                         base::WrapUnique(permission_dict));
+  }
+
+  return permission_dict;
+}
+
+// Records that the user dismissed a permission prompt for type |permission|
+// on |url| to a website setting. Returns the updated number of dismissals.
+int RecordDismissalCount(Profile* profile,
+                         const GURL& url,
+                         content::PermissionType permission) {
+  HostContentSettingsMap* map =
+      HostContentSettingsMapFactory::GetForProfile(profile);
+  std::unique_ptr<base::DictionaryValue> dict = GetOriginDict(map, url);
+
+  base::DictionaryValue* permission_dict = GetOrCreatePermissionDict(
+      dict.get(), PermissionUtil::GetPermissionString(permission));
+
+  int current_count = 0;
+  permission_dict->GetInteger(kPromptDismissCountKey, &current_count);
+  permission_dict->SetInteger(kPromptDismissCountKey, ++current_count);
+
+  map->SetWebsiteSettingDefaultScope(
+      url, GURL(), CONTENT_SETTINGS_TYPE_PROMPT_NO_DECISION_COUNT,
+      std::string(), std::move(dict));
+
+  return current_count;
+}
+
+}  // anonymous namespace

[raymes, 2016/08/01 05:09:11]

nit: I think // namespace is more common

[dominickn, 2016/08/03 05:38:46]

Done.

+
+PermissionPromptDecisionLog::PermissionPromptDecisionLog()
+    : prompt_dismissals_before_block_(kPromptDismissalsBeforeBlock) {
+  UpdateFromVariations();
+}
+
+bool PermissionPromptDecisionLog::ShouldChangeDismissalToBlock(
+    Profile* profile,
+    const GURL& url,
+    content::PermissionType permission) {
+  int current_dismissal_count = RecordDismissalCount(profile, url, permission);
+
+  if (!base::FeatureList::IsEnabled(features::kBlockPromptsIfDismissedOften))
+    return false;
+
+  return current_dismissal_count >= prompt_dismissals_before_block_;
+}
+
+void PermissionPromptDecisionLog::UpdateFromVariations() {
+  int prompt_dismissals = -1;
+  std::string value = variations::GetVariationParamValue(
+      kPromptStudyName, kPromptDismissCountKey);
+
+  // If converting the value fails, stick with the default value.
+  if (base::StringToInt(value, &prompt_dismissals) && prompt_dismissals > 0)
+    prompt_dismissals_before_block_ = prompt_dismissals;
+}