Ensure zero suggest can handle XSSI-escaped output.

chrome/browser/autocomplete/search_provider.cc

Index: chrome/browser/autocomplete/search_provider.cc
diff --git a/chrome/browser/autocomplete/search_provider.cc b/chrome/browser/autocomplete/search_provider.cc
index e4f35813feb91cacb699c4ff33e352afe0dd1845..9228751c8a799a16a1dfbe3d54d54a6c5a33a1ce 100644
--- a/chrome/browser/autocomplete/search_provider.cc
+++ b/chrome/browser/autocomplete/search_provider.cc
@@ -653,24 +653,8 @@ void SearchProvider::OnURLFetchComplete(const net::URLFetcher* source) {
       }
     }
 
-    // The JSON response should be an array.
-    for (size_t response_start_index = json_data.find("["), i = 0;
-         response_start_index != std::string::npos && i < 5;
-         response_start_index = json_data.find("[", 1), i++) {
-      // Remove any XSSI guards to allow for JSON parsing.
-      if (response_start_index > 0)
-        json_data.erase(0, response_start_index);
-
-      JSONStringValueSerializer deserializer(json_data);
-      deserializer.set_allow_trailing_comma(true);
-      int error_code = 0;
-      scoped_ptr<Value> data(deserializer.Deserialize(&error_code, NULL));
-      if (error_code == 0) {
-        results_updated = data.get() &&
-            ParseSuggestResults(data.get(), is_keyword);
-        break;
-      }
-    }
+    scoped_ptr<Value> data(DeserializeJsonData(json_data));
+    results_updated = data.get() && ParseSuggestResults(data.get(), is_keyword);
   }
 
   UpdateMatches();
@@ -1040,6 +1024,26 @@ net::URLFetcher* SearchProvider::CreateSuggestFetcher(
   return fetcher;
 }
 
+scoped_ptr<Value> SearchProvider::DeserializeJsonData(std::string json_data) {
+  // The JSON response should be an array.
+  for (size_t response_start_index = json_data.find("["), i = 0;
+       response_start_index != std::string::npos && i < 5;
+       response_start_index = json_data.find("[", 1), i++) {
+    // Remove any XSSI guards to allow for JSON parsing.
+    if (response_start_index > 0)
+      json_data.erase(0, response_start_index);
+
+    JSONStringValueSerializer deserializer(json_data);
+    deserializer.set_allow_trailing_comma(true);
+    int error_code = 0;
+    scoped_ptr<Value> data(deserializer.Deserialize(&error_code, NULL));
+    if (error_code == 0) {
+      return data.Pass();
+    }
+  }
+  return scoped_ptr<Value>(Value::CreateNullValue());

[H Fung, 2013/12/02 23:04:52]

Are you depending on ParseSuggestResults to fail from the caller in this case
(since I think data.get() will succeed)?  Also, are you depending on RVO since I
don't think scoped_ptr's can be copied?  Or maybe I don't understand how
scoped_ptr works (in Chrome), in which case feel free to ignore this comment.

[Maria, 2013/12/02 23:24:29]

I was actually expecting data.get() to return null in this case. I'll double
check.

As for the scoped_ptr return value, I was following the instructions here:
http://www.chromium.org/developers/smart-pointer-guidelines, which I was
somewhat surprised about as well.

[H Fung, 2013/12/02 23:43:44]

Thanks, it seems like Chrome's scoped_ptr is copyable.

+}
+
 bool SearchProvider::ParseSuggestResults(Value* root_val, bool is_keyword) {
   string16 query;
   ListValue* root_list = NULL;