Send screenshots back to the client for debugging

chrome/test/webdriver/commands/response.cc

Index: chrome/test/webdriver/commands/response.cc
diff --git a/chrome/test/webdriver/commands/response.cc b/chrome/test/webdriver/commands/response.cc
index d25675472c4b27ad217114c5c336856c615c85d2..55a2ffe898cccd8b3a5ea3c80778341ef0a32361 100644
--- a/chrome/test/webdriver/commands/response.cc
+++ b/chrome/test/webdriver/commands/response.cc
@@ -53,13 +53,20 @@ void Response::SetValue(Value* value) {
   data_.Set(kValueKey, value);
 }
 
-void Response::SetError(ErrorCode error_code, const std::string& message,
-                        const std::string& file, int line) {
+void Response::SetError(ErrorCode error_code,
+                        const std::string& message,
+                        const std::string& file,
+                        int line,
+                        const std::string& screenshot) {
   DictionaryValue* error = new DictionaryValue;
   error->SetString(kMessageKey, message);
   error->SetString(kStackTraceFileNameKey, file);
   error->SetInteger(kStackTraceLineNumberKey, line);
 
+  if (!screenshot.empty()) {
+    error->SetString(kScreenKey, screenshot);
+  }
+
   SetStatus(error_code);
   SetValue(error);
 }