Add some suggested performance improvements to geturl.

examples/geturl/geturl_handler.h

 // Copyright (c) 2011 The Native Client 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 EXAMPLES_GETURL_GETURL_HANDLER_H_
 #define EXAMPLES_GETURL_GETURL_HANDLER_H_
 
 #include <string>
 #include "ppapi/cpp/completion_callback.h"
 #include "ppapi/cpp/url_loader.h"
 #include "ppapi/cpp/url_request_info.h"
 #include "ppapi/cpp/instance.h"
 
-#define READ_BUFFER_SIZE 4096
+#define READ_BUFFER_SIZE 32768
 
 // GetURLHandler is used to download data from |url|. When download is
 // finished or when an error occurs, it posts a message back to the browser
 // with the results encoded in the message as a string and self-destroys.
 //
+// pp::URLLoader.GetDownloadProgress() is used to to allocate the memory
+// required for url_response_body_ before the download starts.  (This is not so
+// much of a performance improvement, but it saves some memory since
+// std::string.insert() typically grows the string's capacity by somewhere
+// between 50% to 100% when it needs more memory, depending on the
+// implementation.)  Other performance improvements made as outlined in this
+// bug: http://code.google.com/p/chromium/issues/detail?id=103947
+//
 // EXAMPLE USAGE:
 // GetURLHandler* handler* = GetURLHandler::Create(instance,url);
 // handler->Start();
 //
 class GetURLHandler {
  public:
   // Creates instance of GetURLHandler on the heap.
   // GetURLHandler objects shall be created only on the heap (they
   // self-destroy when all data is in).
   static GetURLHandler* Create(pp::Instance* instance_,
@@ skipping 32 matching lines @@
   // Post a message back to the browser with the download results and
   // self-destroy.  |this| is no longer valid when this method returns.
   void ReportResultAndDie(const std::string& fname,
                           const std::string& text,
                           bool success);
 
   pp::Instance* instance_;  // Weak pointer.
   std::string url_;  // URL to be downloaded.
   pp::URLRequestInfo url_request_;
   pp::URLLoader url_loader_;  // URLLoader provides an API to download URLs.
-  char buffer_[READ_BUFFER_SIZE];  // Temporary buffer for reads.
+  char* buffer_;  // Temporary buffer for reads.
   std::string url_response_body_;  // Contains accumulated downloaded data.
   pp::CompletionCallbackFactory<GetURLHandler> cc_factory_;
 
   GetURLHandler(const GetURLHandler&);
   void operator=(const GetURLHandler&);
 };
 
 #endif  // EXAMPLES_GETURL_GETURL_HANDLER_H_