Modernize some extensions code.

extensions/browser/event_router.h

Index: extensions/browser/event_router.h
diff --git a/extensions/browser/event_router.h b/extensions/browser/event_router.h
index 48bc266980cce4ce121f64a3402d8afbc5926e8a..83bc635e38ba4cacfbb1814b8339ce90a1f11ccf 100644
--- a/extensions/browser/event_router.h
+++ b/extensions/browser/event_router.h
@@ -7,11 +7,11 @@
 
 #include <set>
 #include <string>
+#include <unordered_map>
 #include <utility>
 
 #include "base/callback.h"
 #include "base/compiler_specific.h"
-#include "base/containers/hash_tables.h"
 #include "base/macros.h"
 #include "base/memory/linked_ptr.h"
 #include "base/memory/ref_counted.h"
@@ -72,6 +72,9 @@ class EventRouter : public KeyedService,
     virtual void OnListenerAdded(const EventListenerInfo& details) {}
     // Called when a listener is removed.
     virtual void OnListenerRemoved(const EventListenerInfo& details) {}
+
+   protected:
+    virtual ~Observer() {}
   };
 
   // Gets the EventRouter for |browser_context|.
@@ -126,8 +129,7 @@ class EventRouter : public KeyedService,
   // Registers an observer to be notified when an event listener for
   // |event_name| is added or removed. There can currently be only one observer
   // for each distinct |event_name|.
-  void RegisterObserver(Observer* observer,
-                        const std::string& event_name);
+  void RegisterObserver(Observer* observer, const std::string& event_name);
 
   // Unregisters an observer from all events.
   void UnregisterObserver(Observer* observer);
@@ -157,11 +159,12 @@ class EventRouter : public KeyedService,
                                    bool remove_lazy_listener);
 
   // Returns true if there is at least one listener for the given event.
-  bool HasEventListener(const std::string& event_name);
+  bool HasEventListener(const std::string& event_name) const;
 
   // Returns true if the extension is listening to the given event.
+  // (virtual for testing only.)
   virtual bool ExtensionHasEventListener(const std::string& extension_id,
-                                         const std::string& event_name);
+                                         const std::string& event_name) const;
 
   // Broadcasts an event to every listener registered for that event.
   virtual void BroadcastEvent(std::unique_ptr<Event> event);
@@ -321,11 +324,11 @@ class EventRouter : public KeyedService,
                            int exit_code) override;
   void RenderProcessHostDestroyed(content::RenderProcessHost* host) override;
 
-  content::BrowserContext* browser_context_;
+  content::BrowserContext* const browser_context_;
 
   // The ExtensionPrefs associated with |browser_context_|. May be NULL in
   // tests.
-  ExtensionPrefs* extension_prefs_;
+  ExtensionPrefs* const extension_prefs_;
 
   content::NotificationRegistrar registrar_;
 
@@ -335,7 +338,7 @@ class EventRouter : public KeyedService,
   EventListenerMap listeners_;
 
   // Map from base event name to observer.
-  typedef base::hash_map<std::string, Observer*> ObserverMap;
+  using ObserverMap = std::unordered_map<std::string, Observer*>;
   ObserverMap observers_;
 
   std::set<content::RenderProcessHost*> observed_process_set_;
@@ -346,19 +349,19 @@ class EventRouter : public KeyedService,
 struct Event {
   // This callback should return true if the event should be dispatched to the
   // given context and extension, and false otherwise.
-  typedef base::Callback<bool(content::BrowserContext*,
-                              const Extension*,
-                              Event*,
-                              const base::DictionaryValue*)>
-      WillDispatchCallback;
+  using WillDispatchCallback =
+      base::Callback<bool(content::BrowserContext*,
+                          const Extension*,
+                          Event*,
+                          const base::DictionaryValue*)>;
 
   // The identifier for the event, for histograms. In most cases this
   // correlates 1:1 with |event_name|, in some cases events will generate
   // their own names, but they cannot generate their own identifier.
-  events::HistogramValue histogram_value;
+  const events::HistogramValue histogram_value;
 
   // The event to dispatch.
-  std::string event_name;
+  const std::string event_name;
 
   // Arguments to send to the event listener.
   std::unique_ptr<base::ListValue> event_args;
@@ -423,7 +426,7 @@ struct EventListenerInfo {
 
   const std::string extension_id;
   const GURL listener_url;
-  content::BrowserContext* browser_context;
+  content::BrowserContext* const browser_context;
 };
 
 }  // namespace extensions