Add a global on/off switch for content settings and expose a toggle on the Website Settings options…

chrome/browser/content_settings/content_settings_override_provider.h

Index: chrome/browser/content_settings/content_settings_override_provider.h
diff --git a/chrome/browser/content_settings/content_settings_override_provider.h b/chrome/browser/content_settings/content_settings_override_provider.h
new file mode 100644
index 0000000000000000000000000000000000000000..bcbd3eee61d7e2fc17696a5be999aca445402232
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+++ b/chrome/browser/content_settings/content_settings_override_provider.h
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+// 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_CONTENT_SETTINGS_CONTENT_SETTINGS_OVERRIDE_PROVIDER_H_
+#define CHROME_BROWSER_CONTENT_SETTINGS_CONTENT_SETTINGS_OVERRIDE_PROVIDER_H_
+
+#include "base/macros.h"
+#include "base/synchronization/lock.h"
+#include "components/content_settings/core/browser/content_settings_provider.h"
+#include "components/content_settings/core/common/content_settings_types.h"
+
+class ContentSettingsPattern;
+class PrefService;
+
+namespace user_prefs {
+class PrefRegistrySyncable;
+}
+
+namespace content_settings {
+
+// OverrideProvider contains if certain content settings are enabled or
+// globally disabled. It may only be written to using the UI thread, but may be
+// read on any thread.
+class OverrideProvider : public ProviderInterface {
+ public:
+  static void RegisterProfilePrefs(user_prefs::PrefRegistrySyncable* registry);
+
+  OverrideProvider(PrefService* prefs, bool incognito);
+  virtual ~OverrideProvider();
+
+  // ProviderInterface implementations.
+  virtual RuleIterator* GetRuleIterator(
+      ContentSettingsType content_type,
+      const ResourceIdentifier& resource_identifier,
+      bool incognito) const OVERRIDE;
+
+  virtual void ClearAllContentSettingsRules(
+      ContentSettingsType content_type) OVERRIDE;
+
+  virtual bool SetWebsiteSetting(
+      const ContentSettingsPattern& primary_pattern,
+      const ContentSettingsPattern& secondary_pattern,
+      ContentSettingsType content_type,
+      const ResourceIdentifier& resource_identifier,
+      base::Value* value) OVERRIDE;
+
+  virtual void ShutdownOnUIThread() OVERRIDE;
+
+  // Sets if a given |content_type| is |enabled|.
+  void SetOverrideSetting(ContentSettingsType content_type, bool enabled);
+
+  // Returns if |content_type| is enabled. If it is not enabled, the content
+  // setting type is considered globally disabled and acts as though it is
+  // blocked. If it is enabled, the content setting type's permission is granted
+  // by the other providers.
+  bool IsEnabled(ContentSettingsType content_type) const;
+
+ private:
+  // Reads the override settings from the preferences service.
+  void ReadOverrideSettings();
+
+  // Copies of the pref data, so that we can read it on the IO thread.
+  bool allowed_settings_[CONTENT_SETTINGS_NUM_TYPES];
+
+  PrefService* prefs_;
+
+  bool is_incognito_;
+
+  // Used around accesses to the |override_content_settings_| object to
+  // guarantee thread safety.
+  mutable base::Lock lock_;
+
+  DISALLOW_COPY_AND_ASSIGN(OverrideProvider);
+};
+
+}  // namespace content_settings
+
+#endif  // CHROME_BROWSER_CONTENT_SETTINGS_CONTENT_SETTINGS_OVERRIDE_PROVIDER_H_