Track printer installations for each configuration.

chrome/browser/chromeos/printing/printers_manager.cc

Index: chrome/browser/chromeos/printing/printers_manager.cc
diff --git a/chrome/browser/chromeos/printing/printers_manager.cc b/chrome/browser/chromeos/printing/printers_manager.cc
index 4bcef70c45e7664922e193bd3c1ed25789cbb832..0a382cf07990279e8e0a9261bf34a270daaaeb11 100644
--- a/chrome/browser/chromeos/printing/printers_manager.cc
+++ b/chrome/browser/chromeos/printing/printers_manager.cc
@@ -90,13 +90,9 @@ std::vector<std::unique_ptr<Printer>> PrintersManager::GetRecommendedPrinters()
   std::vector<std::unique_ptr<Printer>> printers;
 
   for (const std::string& key : recommended_printer_ids_) {
-    const base::DictionaryValue& printer_dictionary =
-        *(recommended_printers_.at(key));
-    std::unique_ptr<Printer> printer =
-        printing::RecommendedPrinterToPrinter(printer_dictionary);
-    if (printer) {
-      printer->set_source(Printer::SRC_POLICY);
-      printers.push_back(std::move(printer));
+    auto printer = recommended_printers_.find(key);
+    if (printer != recommended_printers_.end()) {
+      printers.push_back(base::MakeUnique<Printer>(*printer->second));
     }
   }
 
@@ -108,8 +104,10 @@ std::unique_ptr<Printer> PrintersManager::GetPrinter(
   // check for a policy printer first
   const auto& policy_printers = recommended_printers_;
   auto found = policy_printers.find(printer_id);
-  if (found != policy_printers.end())
-    return printing::RecommendedPrinterToPrinter(*(found->second));
+  if (found != policy_printers.end()) {
+    // Copy a printer.
+    return base::MakeUnique<Printer>(*(found->second));
+  }
 
   base::Optional<sync_pb::PrinterSpecifics> printer =
       sync_bridge_->GetPrinter(printer_id);
@@ -176,8 +174,11 @@ void PrintersManager::UpdateRecommendedPrinters() {
 
   const base::ListValue* values =
       prefs->GetList(prefs::kRecommendedNativePrinters);
+  const base::Time timestamp = base::Time::Now();
 
-  recommended_printer_ids_.clear();
+  // Parse the policy JSON into new structures.
+  std::vector<std::string> new_ids;
+  std::map<std::string, std::unique_ptr<Printer>> new_printers;
   for (const auto& value : *values) {
     std::string printer_json;
     if (!value.GetAsString(&printer_json)) {
@@ -201,9 +202,36 @@ void PrintersManager::UpdateRecommendedPrinters() {
     std::string id = base::MD5String(printer_json);
     printer_dictionary->SetString(printing::kPrinterId, id);
 
-    recommended_printer_ids_.push_back(id);
-    recommended_printers_[id] = std::move(printer_dictionary);
+    new_ids.push_back(id);
+    // Move existing printers, create othewise.
+    auto old = recommended_printers_.find(id);
+    if (old != recommended_printers_.end()) {

[Carlson, 2017/05/08 21:01:17]

Generally looks fine, but back to my original comment, I think this behaves
badly if we have multiple entries for the same printer.  We'll end up moving the
existing entry into the new map twice, which will cause the entry in
new_printers to be null.

You could just erase the entry from the existing map after you move it to avoid
this, or do something else, but I think it's worth taking care of this.

[skau, 2017/05/08 21:19:25]

We expect all printer entries to be unique within the collection.  But I'll skip
duplicates to avoid this scenario.

+      new_printers[id] = std::move(old->second);
+    } else {
+      auto printer =
+          printing::RecommendedPrinterToPrinter(*printer_dictionary, timestamp);
+      printer->set_source(Printer::SRC_POLICY);
+
+      new_printers[id] = std::move(printer);
+    }
   }
+
+  // Objects not in the most recent update get deallocated after method exit.
+  recommended_printer_ids_.swap(new_ids);
+  recommended_printers_.swap(new_printers);
+}
+
+void PrintersManager::PrinterInstalled(const Printer& printer) {
+  DCHECK(!printer.last_updated().is_null());
+  installed_printer_timestamps_[printer.id()] = printer.last_updated();
+}
+
+bool PrintersManager::IsConfigurationCurrent(const Printer& printer) {
+  auto found = installed_printer_timestamps_.find(printer.id());
+  if (found == installed_printer_timestamps_.end())
+    return false;
+
+  return found->second == printer.last_updated();
 }
 
 }  // namespace chromeos