Don't crash on device resolution failure.

chrome/browser/local_discovery/privet_local_printer_lister.cc

Index: chrome/browser/local_discovery/privet_local_printer_lister.cc
diff --git a/chrome/browser/local_discovery/privet_local_printer_lister.cc b/chrome/browser/local_discovery/privet_local_printer_lister.cc
index 2dc8fa9b6bd2c1c53bd4cd5318eb72ad8b95af59..f9ffb43709fc40408fe4b8eb150af42fdc0c227c 100644
--- a/chrome/browser/local_discovery/privet_local_printer_lister.cc
+++ b/chrome/browser/local_discovery/privet_local_printer_lister.cc
@@ -13,11 +13,7 @@
 namespace local_discovery {
 
 struct PrivetLocalPrinterLister::DeviceContext {
- public:
-  DeviceContext() {
-  }
-
-  ~DeviceContext() {
+  DeviceContext() : has_local_printing(false) {
   }
 
   scoped_ptr<PrivetHTTPResolution> privet_resolution;
@@ -71,7 +67,7 @@ void PrivetLocalPrinterLister::DeviceChanged(
         name,
         description.address,
         base::Bind(&PrivetLocalPrinterLister::OnPrivetResolved,
-                   base::Unretained(this)));
+                   base::Unretained(this), name));
 
     device_contexts_[name] = context;
     context->privet_resolution->Start();
@@ -84,7 +80,13 @@ void PrivetLocalPrinterLister::DeviceCacheFlushed() {
 }
 
 void PrivetLocalPrinterLister::OnPrivetResolved(
+    const std::string& name,
     scoped_ptr<PrivetHTTPClient> http_client) {
+  if (!http_client) {
+    // Remove device if we can't resolve it.
+    device_contexts_.erase(name);
+    return;
+  }
   DeviceContextMap::iterator i = device_contexts_.find(http_client->GetName());
   DCHECK(i != device_contexts_.end());
 
@@ -99,7 +101,7 @@ void PrivetLocalPrinterLister::OnPrivetResolved(
 
 void PrivetLocalPrinterLister::OnPrivetInfoDone(
     DeviceContext* context,
-    std::string name,
+    const std::string& name,
     const base::DictionaryValue* json_value) {
   bool has_local_printing = false;
   const base::ListValue* api_list = NULL;