Revert of Signal extension API schema corruption to the browser process.

extensions/common/extension_api.h

 // Copyright 2013 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 EXTENSIONS_COMMON_EXTENSION_API_H_
 #define EXTENSIONS_COMMON_EXTENSION_API_H_
 
 #include <map>
 #include <memory>
 #include <string>
@@ skipping 88 matching lines @@
   // Determines whether an API, or any parts of that API, are available in
   // |context|.
   bool IsAnyFeatureAvailableToContext(const Feature& api,
                                       const Extension* extension,
                                       Feature::Context context,
                                       const GURL& url);
 
   // Returns true if |name| is available to WebUI contexts on |url|.
   bool IsAvailableToWebUI(const std::string& name, const GURL& url);
 
-  // Gets the schema for the extension API with namespace |full_name|, or
-  // nullptr if the schema could not be loaded.
+  // Gets the schema for the extension API with namespace |full_name|.
   // Ownership remains with this object.
   const base::DictionaryValue* GetSchema(const std::string& full_name);
 
   // Splits a full name from the extension API into its API and child name
   // parts. Some examples:
   //
   // "bookmarks.create" -> ("bookmarks", "create")
   // "experimental.input.ui.cursorUp" -> ("experimental.input.ui", "cursorUp")
   // "storage.sync.set" -> ("storage", "sync.get")
   // "<unknown-api>.monkey" -> ("", "")
@@ skipping 31 matching lines @@
   // FeatureProviders used for resolving dependencies.
   typedef std::map<std::string, const FeatureProvider*> FeatureProviderMap;
   FeatureProviderMap dependency_providers_;
 
   DISALLOW_COPY_AND_ASSIGN(ExtensionAPI);
 };
 
 }  // namespace extensions
 
 #endif  // EXTENSIONS_COMMON_EXTENSION_API_H_