Added unit test for DevTools' ephemeral port support.

content/browser/devtools/devtools_http_handler_impl.cc

Index: content/browser/devtools/devtools_http_handler_impl.cc
diff --git a/content/browser/devtools/devtools_http_handler_impl.cc b/content/browser/devtools/devtools_http_handler_impl.cc
index 1b9da1d2e744a426ca937d4272424974d3040010..bd1be4b0dc7ce7611234c174ddbf1b762539be91 100644
--- a/content/browser/devtools/devtools_http_handler_impl.cc
+++ b/content/browser/devtools/devtools_http_handler_impl.cc
@@ -5,7 +5,6 @@
 #include "content/browser/devtools/devtools_http_handler_impl.h"
 
 #include <algorithm>
-#include <sstream>
 #include <utility>
 
 #include "base/bind.h"
@@ -15,6 +14,7 @@
 #include "base/logging.h"
 #include "base/message_loop/message_loop_proxy.h"
 #include "base/stl_util.h"
+#include "base/strings/string_number_conversions.h"
 #include "base/threading/thread.h"
 #include "base/values.h"
 #include "content/browser/devtools/devtools_browser_target.h"
@@ -699,10 +699,8 @@ void DevToolsHttpHandlerImpl::WriteActivePortToUserProfile() {
   // so Telemetry can pick it up.
   base::FilePath path = active_port_output_directory_.Append(
       kDevToolsActivePortFileName);
-  std::stringstream port_stream;
-  port_stream << endpoint.port();
-  std::string s = port_stream.str();
-  if (base::WriteFile(path, s.c_str(), s.length()) < 0) {
+  std::string port_string = base::IntToString(endpoint.port());
+  if (base::WriteFile(path, port_string.c_str(), port_string.length()) < 0) {
     LOG(ERROR) << "Error writing DevTools active port to file";
   }
 }