Implement mediaGalleriesPrivate api to notify extensions about gallery changed events.

chrome/browser/extensions/api/media_galleries_private/media_galleries_private_event_router.cc

Index: chrome/browser/extensions/api/media_galleries_private/media_galleries_private_event_router.cc
diff --git a/chrome/browser/extensions/api/media_galleries_private/media_galleries_private_event_router.cc b/chrome/browser/extensions/api/media_galleries_private/media_galleries_private_event_router.cc
index b270fad6a5104d53cc21f0fafd6feb3abd8f8256..fe7f002400fa54aefbba4d7cab4efa70adc33eb7 100644
--- a/chrome/browser/extensions/api/media_galleries_private/media_galleries_private_event_router.cc
+++ b/chrome/browser/extensions/api/media_galleries_private/media_galleries_private_event_router.cc
@@ -9,6 +9,7 @@
 #include <map>
 
 #include "base/utf_string_conversions.h"
+#include "base/values.h"
 #include "chrome/browser/browser_process.h"
 #include "chrome/browser/extensions/event_names.h"
 #include "chrome/browser/extensions/event_router.h"
@@ -16,6 +17,7 @@
 #include "chrome/browser/media_gallery/media_file_system_registry.h"
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/common/extensions/api/media_galleries_private.h"
+#include "content/public/browser/browser_thread.h"
 
 namespace extensions {
 
@@ -31,27 +33,59 @@ std::string GetTransientIdForDeviceId(const std::string& device_id) {
 
 using extensions::api::media_galleries_private::DeviceAttachmentDetails;
 using extensions::api::media_galleries_private::DeviceDetachmentDetails;
+using extensions::api::media_galleries_private::GalleryChangeDetails;
 
 MediaGalleriesPrivateEventRouter::MediaGalleriesPrivateEventRouter(
     Profile* profile)
     : profile_(profile) {
-  CHECK(profile_);
-
+  DCHECK(profile_);
+  DCHECK(content::BrowserThread::CurrentlyOn(content::BrowserThread::UI));
   base::SystemMonitor* system_monitor = base::SystemMonitor::Get();
   if (system_monitor)
     system_monitor->AddDevicesChangedObserver(this);
 }
 
 MediaGalleriesPrivateEventRouter::~MediaGalleriesPrivateEventRouter() {
+  DCHECK(content::BrowserThread::CurrentlyOn(content::BrowserThread::UI));
   base::SystemMonitor* system_monitor = base::SystemMonitor::Get();
   if (system_monitor)
     system_monitor->RemoveDevicesChangedObserver(this);
 }
 
+void MediaGalleriesPrivateEventRouter::OnGalleryChanged(
+    chrome::MediaGalleryPrefId gallery_id,
+    const std::set<std::string>& extension_ids) {
+  DCHECK(content::BrowserThread::CurrentlyOn(content::BrowserThread::UI));
+  EventRouter* router =
+      extensions::ExtensionSystem::Get(profile_)->event_router();
+  if (!router->HasEventListener(event_names::kOnGalleryChangedEventName))
+    return;
+
+  for (std::set<std::string>::const_iterator it = extension_ids.begin();
+       it != extension_ids.end(); ++it) {
+    GalleryChangeDetails details;
+    details.gallery_id = gallery_id;
+    scoped_ptr<ListValue> args(new ListValue());
+    args->Append(details.ToValue().release());
+    scoped_ptr<extensions::Event> event(new extensions::Event(
+        event_names::kOnGalleryChangedEventName,
+        args.Pass()));
+    // Use DispatchEventToExtension() instead of BroadcastEvent().
+    // BroadcastEvent() sends the gallery changed events to all the extensions
+    // who have added a listener to the onGalleryChanged event. There is a
+    // chance that an extension might have added an onGalleryChanged() listener
+    // without calling addGalleryWatch(). Therefore, use
+    // DispatchEventToExtension() to dispatch the gallery changed event only to
+    // the watching extensions.
+    router->DispatchEventToExtension(*it, event.Pass());
+  }
+}
+
 void MediaGalleriesPrivateEventRouter::OnRemovableStorageAttached(
     const std::string& id,
     const string16& name,
     const FilePath::StringType& location) {
+  DCHECK(content::BrowserThread::CurrentlyOn(content::BrowserThread::UI));
   EventRouter* router =
       extensions::ExtensionSystem::Get(profile_)->event_router();
   if (!router->HasEventListener(event_names::kOnAttachEventName))
@@ -68,6 +102,7 @@ void MediaGalleriesPrivateEventRouter::OnRemovableStorageAttached(
 
 void MediaGalleriesPrivateEventRouter::OnRemovableStorageDetached(
     const std::string& id) {
+  DCHECK(content::BrowserThread::CurrentlyOn(content::BrowserThread::UI));
   EventRouter* router =
       extensions::ExtensionSystem::Get(profile_)->event_router();
   if (!router->HasEventListener(event_names::kOnDetachEventName))
@@ -84,6 +119,7 @@ void MediaGalleriesPrivateEventRouter::OnRemovableStorageDetached(
 void MediaGalleriesPrivateEventRouter::DispatchEvent(
     const std::string& event_name,
     scoped_ptr<base::ListValue> event_args) {
+  DCHECK(content::BrowserThread::CurrentlyOn(content::BrowserThread::UI));
   EventRouter* router =
       extensions::ExtensionSystem::Get(profile_)->event_router();
   if (!router)