Reland r223124: Don't clear existing extension-defined preferences and content settings when reload…

chrome/browser/extensions/extension_pref_value_map.cc

Index: chrome/browser/extensions/extension_pref_value_map.cc
diff --git a/chrome/browser/extensions/extension_pref_value_map.cc b/chrome/browser/extensions/extension_pref_value_map.cc
index c497e5ad1cb65d29cb1dee8bdf09f1c1094fe1e1..d8521e56aafe48e7ef3df8e4a9941c604cc4f81d 100644
--- a/chrome/browser/extensions/extension_pref_value_map.cc
+++ b/chrome/browser/extensions/extension_pref_value_map.cc
@@ -116,10 +116,13 @@ bool ExtensionPrefValueMap::DoesExtensionControlPref(
 void ExtensionPrefValueMap::RegisterExtension(const std::string& ext_id,
                                               const base::Time& install_time,
                                               bool is_enabled) {
-  if (entries_.find(ext_id) != entries_.end())
-    UnregisterExtension(ext_id);
-  entries_[ext_id] = new ExtensionEntry;
-  entries_[ext_id]->install_time = install_time;
+  if (entries_.find(ext_id) == entries_.end()) {
+    entries_[ext_id] = new ExtensionEntry;
+
+    // Only update the install time if the extension is newly installed.
+    entries_[ext_id]->install_time = install_time;
+  }
+
   entries_[ext_id]->enabled = is_enabled;
 }