Avoid a string copy in URLRequestResourceBundleJob::GetData().

net/url_request/url_request_simple_job.h

Index: net/url_request/url_request_simple_job.h
diff --git a/net/url_request/url_request_simple_job.h b/net/url_request/url_request_simple_job.h
index 85d8f7e39edfa29edbdf26e7be96cccb11e157cc..734b99838a91fd68ef71de35713229bcd2615494 100644
--- a/net/url_request/url_request_simple_job.h
+++ b/net/url_request/url_request_simple_job.h
@@ -8,6 +8,7 @@
 #include <string>
 
 #include "base/memory/weak_ptr.h"
+#include "base/strings/string_piece.h"
 #include "net/base/completion_callback.h"
 #include "net/base/net_export.h"
 #include "net/url_request/url_range_request_job.h"
@@ -41,7 +42,13 @@ class NET_EXPORT URLRequestSimpleJob : public URLRangeRequestJob {
   virtual int GetData(std::string* mime_type,
                       std::string* charset,
                       std::string* data,
-                      const CompletionCallback& callback) const = 0;
+                      const CompletionCallback& callback) const;
+  // Similar to GetData(), except the subclass must ensure that the characters
+  // referred to by *data live at least as long as *this.
+  virtual int GetStringPieceData(std::string* mime_type,
+                                 std::string* charset,
+                                 base::StringPiece* data,
+                                 const CompletionCallback& callback);

[mmenke, 2014/11/14 22:46:40]

Could be instead take a base::RefCountedMemory?  See
ResourceBundle::LoadDataResourceBytes[ForScale]?

That may allow other cases of dynamically created data to avoid a copy, too.

[Jeffrey Yasskin, 2014/11/15 02:34:20]

Ah, that's definitely better; thanks! I'm inclined to switch the rest of the
implementations of GetData() over to RefCountedMemory too, but to do that in a
separate patch after we've seen that this patch fixes the problem.

 
  protected:
   void StartAsync();
@@ -52,7 +59,8 @@ class NET_EXPORT URLRequestSimpleJob : public URLRangeRequestJob {
   HttpByteRange byte_range_;
   std::string mime_type_;
   std::string charset_;
-  std::string data_;
+  std::string data_storage_;
+  base::StringPiece data_;
   int data_offset_;
   base::WeakPtrFactory<URLRequestSimpleJob> weak_factory_;
 };