Implement chrome.experimental.downloads.onChanged

chrome/browser/extensions/extension_downloads_api.h

Index: chrome/browser/extensions/extension_downloads_api.h
diff --git a/chrome/browser/extensions/extension_downloads_api.h b/chrome/browser/extensions/extension_downloads_api.h
index b0cf0e90cc3db310d6ae215aa9250fcfbb2156c4..466b31e06bedb767cea0ab4e96994d04527a8d59 100644
--- a/chrome/browser/extensions/extension_downloads_api.h
+++ b/chrome/browser/extensions/extension_downloads_api.h
@@ -12,6 +12,7 @@
 
 #include "base/file_path.h"
 #include "base/memory/singleton.h"
+#include "base/stl_util.h"
 #include "base/string16.h"
 #include "chrome/browser/extensions/extension_function.h"
 #include "content/browser/download/download_item.h"
@@ -255,22 +256,40 @@ class DownloadsDragFunction : public AsyncDownloadsFunction {
   DISALLOW_COPY_AND_ASSIGN(DownloadsDragFunction);
 };
 
-class ExtensionDownloadsEventRouter : public DownloadManager::Observer {
+// Observes a single DownloadManager and many DownloadItems and dispatches
+// onCreated and onErased events.
+class ExtensionDownloadsEventRouter : public DownloadManager::Observer,
+                                      public DownloadItem::Observer {
  public:
   explicit ExtensionDownloadsEventRouter(Profile* profile);
   virtual ~ExtensionDownloadsEventRouter();
 
   virtual void ModelChanged() OVERRIDE;
   virtual void ManagerGoingDown() OVERRIDE;
+  virtual void OnDownloadUpdated(DownloadItem* download) OVERRIDE;
+  virtual void OnDownloadOpened(DownloadItem* download) OVERRIDE;
 
  private:
+  struct OnChangedStat {
+    OnChangedStat();
+    ~OnChangedStat();
+    int fires;
+    int total;
+  };
+
+  typedef std::map<int, DownloadItem*> ItemMap;
+  typedef std::map<int, base::DictionaryValue*> ItemJsonMap;
+  typedef std::map<int, OnChangedStat*> OnChangedStatMap;
+
   void DispatchEvent(const char* event_name, base::Value* json_arg);
-  typedef base::hash_map<int, DownloadItem*> ItemMap;
-  typedef std::set<int> DownloadIdSet;
 
   Profile* profile_;
   DownloadManager* manager_;
-  DownloadIdSet downloads_;
+  ItemMap downloads_;
+  ItemJsonMap item_jsons_;
+  STLValueDeleter<ItemJsonMap> delete_item_jsons_;
+  OnChangedStatMap on_changed_stats_;
+  STLValueDeleter<OnChangedStatMap> delete_on_changed_stats_;
 
   DISALLOW_COPY_AND_ASSIGN(ExtensionDownloadsEventRouter);
 };