[Extensions] Update extensions UI to observe events and add test

chrome/browser/extensions/api/developer_private/extension_info_generator.cc

Index: chrome/browser/extensions/api/developer_private/extension_info_generator.cc
diff --git a/chrome/browser/extensions/api/developer_private/extension_info_generator.cc b/chrome/browser/extensions/api/developer_private/extension_info_generator.cc
index 81bf3a5684a2079847a541afb504588a20ea87d3..45817278c2fdf3e0cba2b89eab9b35f1034a416c 100644
--- a/chrome/browser/extensions/api/developer_private/extension_info_generator.cc
+++ b/chrome/browser/extensions/api/developer_private/extension_info_generator.cc
@@ -71,8 +71,7 @@ developer::ExtensionType GetExtensionType(Manifest::Type manifest_type) {
 
 // Populates the common fields of an extension error.
 template <typename ErrorType>
-void PopulateErrorBase(const ExtensionError& error,
-                       ErrorType* out) {
+void PopulateErrorBase(const ExtensionError& error, ErrorType* out) {
   CHECK(out);
   out->type = error.type() == ExtensionError::MANIFEST_ERROR ?
       developer::ERROR_TYPE_MANIFEST : developer::ERROR_TYPE_RUNTIME;
@@ -365,6 +364,25 @@ ExtensionInfoGenerator::CreateExtensionInfo(const Extension& extension,
   return info.Pass();
 }
 
+scoped_ptr<api::developer_private::ExtensionInfo>
+ExtensionInfoGenerator::CreateExtensionInfo(const std::string& id) {
+  developer::ExtensionState state = developer::EXTENSION_STATE_ENABLED;
+  ExtensionRegistry* registry = ExtensionRegistry::Get(browser_context_);
+  const Extension* extension = registry->enabled_extensions().GetByID(id);
+  if (!extension &&
+      (extension = registry->disabled_extensions().GetByID(id)) != nullptr) {
+    state = developer::EXTENSION_STATE_DISABLED;
+  } else if (!extension &&
+             (extension =
+                  registry->terminated_extensions().GetByID(id)) != nullptr) {
+    state = developer::EXTENSION_STATE_TERMINATED;
+  }
+  scoped_ptr<api::developer_private::ExtensionInfo> info;
+  if (extension)
+    info = CreateExtensionInfo(*extension, state);
+  return info.Pass();
+}
+
 ExtensionInfoGenerator::ExtensionInfoList
 ExtensionInfoGenerator::CreateExtensionsInfo(bool include_disabled,
                                              bool include_terminated) {