[ios] Adds an Initialize() method to OmahaServiceProvider.

ios/public/provider/chrome/browser/omaha/omaha_service_provider.h

 // 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.
 
 #ifndef IOS_PUBLIC_PROVIDER_CHROME_BROWSER_OMAHA_OMAHA_SERVICE_PROVIDER_H_
 #define IOS_PUBLIC_PROVIDER_CHROME_BROWSER_OMAHA_OMAHA_SERVICE_PROVIDER_H_
 
 #include <string>
 
 #include "base/macros.h"
 #include "url/gurl.h"
 
 class OmahaXmlWriter;
 
 // OmahaServiceProvider provides the OmahaService with URLs and other data that
 // are necessary to send update requests.
 class OmahaServiceProvider {
  public:
   OmahaServiceProvider();
   virtual ~OmahaServiceProvider();
 
+  // Initializes the provider.  This method will be called on the UI thread.
+  virtual void Initialize();
+
   // Returns the URL to use for update checks.
   virtual GURL GetUpdateServerURL() const;
 
   // Returns the unique ID for this application. The returned value may depend
   // on bundle id, channel, or form factor.
   virtual std::string GetApplicationID() const;
 
   // Returns the default brand code for this installation.  The returned value
   // may depend on bundle id, channel, or form factor.  Returns the empty string
   // if this installation is not associated with a brand code.
   virtual std::string GetBrandCode() const;
 
   // Allows the embedder to append embedder-specific attributes to the XML
   // request.  This method may be called multiple times per request.  Embedders
   // should only add attributes that are relevant for the given element |tag|.
   virtual void AppendExtraAttributes(const std::string& tag,
                                      OmahaXmlWriter* writer) const;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(OmahaServiceProvider);
 };
 
 #endif  // IOS_PUBLIC_PROVIDER_CHROME_BROWSER_OMAHA_OMAHA_SERVICE_PROVIDER_H_