Native api to get OAuth2 access tokens in Print Preview Web UI.

chrome/browser/ui/webui/print_preview/print_preview_handler.h

Index: chrome/browser/ui/webui/print_preview/print_preview_handler.h
diff --git a/chrome/browser/ui/webui/print_preview/print_preview_handler.h b/chrome/browser/ui/webui/print_preview/print_preview_handler.h
index 71658a7a1e677d5602b06a821280df3534daa9c9..788d99a0fe25fa4f4e70486753a55e7db494a495 100644
--- a/chrome/browser/ui/webui/print_preview/print_preview_handler.h
+++ b/chrome/browser/ui/webui/print_preview/print_preview_handler.h
@@ -115,6 +115,9 @@ class PrintPreviewHandler : public content::WebUIMessageHandler,
   // |args| is unused.
   void HandleSignin(const base::ListValue* args);
 
+  // Generates new token and sends back to UI.
+  void HandleGetAccessToken(const base::ListValue* args);
+
   // Brings up a web page to allow the user to configure cloud print.
   // |args| is unused.
   void HandleManageCloudPrint(const base::ListValue* args);
@@ -151,6 +154,10 @@ class PrintPreviewHandler : public content::WebUIMessageHandler,
       const std::string& default_printer,
       const std::string& cloud_print_data);
 
+  // Send OAuth2 access token.
+  void SendAccessToken(const std::string& type,
+                       const std::string& access_token);
+
   // Sends the printer capabilities to the Web UI. |settings_info| contains
   // printer capabilities information.
   void SendPrinterCapabilities(const base::DictionaryValue& settings_info);
@@ -198,6 +205,8 @@ class PrintPreviewHandler : public content::WebUIMessageHandler,
   bool GetPreviewDataAndTitle(scoped_refptr<base::RefCountedBytes>* data,
                               string16* title) const;
 
+  void InitTokenService();
+
   // Pointer to current print system.
   scoped_refptr<printing::PrintBackend> print_backend_;
 
@@ -222,6 +231,10 @@ class PrintPreviewHandler : public content::WebUIMessageHandler,
   // exists.
   scoped_ptr<base::FilePath> print_to_pdf_path_;
 
+  // Holds token service to get OAuth2 access tokens.
+  class AccessTokenService;
+  scoped_ptr<AccessTokenService> token_service_;
+
   DISALLOW_COPY_AND_ASSIGN(PrintPreviewHandler);
 };