Add experiment to measure time to hash extension content as we read it

net/url_request/url_request_file_job.cc

Index: net/url_request/url_request_file_job.cc
diff --git a/net/url_request/url_request_file_job.cc b/net/url_request/url_request_file_job.cc
index 7db8d818836bf77fb9398a1f3cbd4327f5030e4a..fffdc0789e89db4b1d926b3ecc74b578a6f66bb8 100644
--- a/net/url_request/url_request_file_job.cc
+++ b/net/url_request/url_request_file_job.cc
@@ -83,8 +83,9 @@ void URLRequestFileJob::Kill() {
   URLRequestJob::Kill();
 }
 
-bool URLRequestFileJob::ReadRawData(IOBuffer* dest, int dest_size,
-                                    int *bytes_read) {
+bool URLRequestFileJob::ReadRawData(IOBuffer* dest,
+                                    int dest_size,
+                                    int* bytes_read) {
   DCHECK_NE(dest_size, 0);
   DCHECK(bytes_read);
   DCHECK_GE(remaining_bytes_, 0);
@@ -99,9 +100,11 @@ bool URLRequestFileJob::ReadRawData(IOBuffer* dest, int dest_size,
     return true;
   }
 
-  int rv = stream_->Read(dest, dest_size,
+  int rv = stream_->Read(dest,
+                         dest_size,
                          base::Bind(&URLRequestFileJob::DidRead,
-                                    weak_ptr_factory_.GetWeakPtr()));
+                                    weak_ptr_factory_.GetWeakPtr(),
+                                    make_scoped_refptr(dest)));
   if (rv >= 0) {
     // Data is immediately available.
     *bytes_read = rv;
@@ -192,6 +195,12 @@ void URLRequestFileJob::SetExtraRequestHeaders(
   }
 }
 
+void URLRequestFileJob::OnSeekComplete(int64 result) {
+}
+
+void URLRequestFileJob::OnReadComplete(net::IOBuffer* buf, int result) {
+}
+
 URLRequestFileJob::~URLRequestFileJob() {
 }
 
@@ -273,6 +282,7 @@ void URLRequestFileJob::DidOpen(int result) {
 }
 
 void URLRequestFileJob::DidSeek(int64 result) {
+  OnSeekComplete(result);
   if (result != byte_range_.first_byte_position()) {
     NotifyDone(URLRequestStatus(URLRequestStatus::FAILED,
                                 ERR_REQUEST_RANGE_NOT_SATISFIABLE));
@@ -283,7 +293,9 @@ void URLRequestFileJob::DidSeek(int64 result) {
   NotifyHeadersComplete();
 }
 
-void URLRequestFileJob::DidRead(int result) {
+void URLRequestFileJob::DidRead(scoped_refptr<net::IOBuffer> buf, int result) {
+  OnReadComplete(buf.get(), result);
+  buf = NULL;
   if (result > 0) {
     SetStatus(URLRequestStatus());  // Clear the IO_PENDING status
   } else if (result == 0) {