Improve error messaging of webRequest API in case of conflicts

chrome/browser/extensions/extension_warning_service.h

Index: chrome/browser/extensions/extension_warning_service.h
diff --git a/chrome/browser/extensions/extension_warning_service.h b/chrome/browser/extensions/extension_warning_service.h
new file mode 100644
index 0000000000000000000000000000000000000000..03e8499bc4b2f7daf3ace181219a01cd726f478d
--- /dev/null
+++ b/chrome/browser/extensions/extension_warning_service.h
@@ -0,0 +1,92 @@
+// Copyright (c) 2012 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_EXTENSIONS_EXTENSION_WARNING_SERVICE_H_
+#define CHROME_BROWSER_EXTENSIONS_EXTENSION_WARNING_SERVICE_H_
+
+#include <set>
+#include <string>
+#include <vector>
+
+#include "base/observer_list.h"
+#include "base/threading/non_thread_safe.h"
+#include "chrome/browser/extensions/extension_warning_set.h"
+#include "chrome/common/extensions/extension_set.h"
+#include "content/public/browser/notification_observer.h"
+#include "content/public/browser/notification_registrar.h"
+
+// TODO(battre) Remove the Extension prefix.
+
+class Profile;
+
+namespace content {
+class NotificationDetails;
+class NotificationSource;
+}
+
+namespace extensions {
+
+// Manages a set of warnings caused by extensions. These warnings (e.g.
+// conflicting modifications of network requests by extensions, slow extensions,
+// etc.) trigger a warning badge in the UI and and provide means to resolve
+// them. This class must be used on the UI thread only.
+class ExtensionWarningService : public content::NotificationObserver,
+                                public base::NonThreadSafe {
+ public:
+  class Observer {
+   public:
+    virtual void ExtensionWarningsChanged() = 0;
+  };
+
+  // |profile| may be NULL for testing. In this case, be sure to not insert
+  // any warnings.
+  explicit ExtensionWarningService(Profile* profile);
+  virtual ~ExtensionWarningService();
+
+  // Clears all warnings of types contained in |types| and notifies observers
+  // of the changed warnings.
+  void ClearWarnings(const std::set<ExtensionWarning::WarningType>& types);
+
+  // Returns all types of warnings effecting extension |extension_id|.
+  std::set<ExtensionWarning::WarningType> GetWarningTypesAffectingExtension(
+      const std::string& extension_id) const;
+
+  // Returns all localized warnings for extension |extension_id| in |result|.
+  std::vector<std::string> GetWarningMessagesForExtension(
+      const std::string& extension_id) const;
+
+  const ExtensionWarningSet& warnings() const { return warnings_; }
+
+  // Adds a set of warnings and notifies observers if any warning is new.
+  void AddWarnings(const ExtensionWarningSet& warnings);
+
+  // Notifies the ExtensionWarningService of profile |profile_id| that new
+  // |warnings| occurred and triggers a warning badge.
+  static void NotifyWarningsOnUI(void* profile_id,
+                                 const ExtensionWarningSet& warnings);
+
+  void AddObserver(Observer* observer);
+  void RemoveObserver(Observer* observer);
+
+ private:
+  void NotifyWarningsChanged();
+
+  // Implementation for content::NotificationObserver.
+  virtual void Observe(int type,
+                       const content::NotificationSource& source,
+                       const content::NotificationDetails& details) OVERRIDE;
+
+  // Currently existing warnings.
+  ExtensionWarningSet warnings_;
+
+  content::NotificationRegistrar registrar_;
+
+  Profile* profile_;
+
+  ObserverList<Observer> observer_list_;
+};
+
+}  // namespace extensions
+
+#endif  // CHROME_BROWSER_EXTENSIONS_EXTENSION_WARNING_SERVICE_H_