Revert of Rate limit programmatic update checks for extensions

chrome/browser/extensions/updater/extension_updater.h

Index: chrome/browser/extensions/updater/extension_updater.h
diff --git a/chrome/browser/extensions/updater/extension_updater.h b/chrome/browser/extensions/updater/extension_updater.h
index 92851e8c351fb8c2f26e6ec63bc845454399e542..d2568296e1b6fc520220de2e2b083c9269d51ea7 100644
--- a/chrome/browser/extensions/updater/extension_updater.h
+++ b/chrome/browser/extensions/updater/extension_updater.h
@@ -56,6 +56,7 @@
 // ....
 // updater->Stop();
 class ExtensionUpdater : public ExtensionDownloaderDelegate,
+                         public ExtensionRegistryObserver,
                          public content::NotificationObserver {
  public:
   typedef base::Closure FinishedCallback;
@@ -103,8 +104,10 @@
   // already a pending task that has not yet run.
   void CheckSoon();
 
-  // Starts an update check for the specified extension soon.
-  void CheckExtensionSoon(const std::string& extension_id,
+  // Starts an update check for the specified extension soon. If a check
+  // is already running, or finished too recently without an update being
+  // installed, this method returns false and the check won't be scheduled.
+  bool CheckExtensionSoon(const std::string& extension_id,
                           const FinishedCallback& callback);
 
   // Starts an update check right now, instead of waiting for the next
@@ -154,6 +157,8 @@
     // The ids of extensions that have in-progress update checks.
     std::list<std::string> in_progress_ids_;
   };
+
+  struct ThrottleInfo;
 
   // Ensure that we have a valid ExtensionDownloader instance referenced by
   // |downloader|.
@@ -209,6 +214,12 @@
                const content::NotificationSource& source,
                const content::NotificationDetails& details) override;
 
+  // Implementation of ExtensionRegistryObserver.
+  void OnExtensionWillBeInstalled(content::BrowserContext* browser_context,
+                                  const Extension* extension,
+                                  bool is_update,
+                                  const std::string& old_name) override;
+
   // Send a notification that update checks are starting.
   void NotifyStarted();
 
@@ -245,6 +256,9 @@
   // Observes CRX installs we initiate.
   content::NotificationRegistrar registrar_;
 
+  ScopedObserver<ExtensionRegistry, ExtensionRegistryObserver>
+      extension_registry_observer_;
+
   // True when a CrxInstaller is doing an install.  Used in MaybeUpdateCrxFile()
   // to keep more than one install from running at once.
   bool crx_install_is_running_;
@@ -255,6 +269,10 @@
 
   ExtensionCache* extension_cache_;
 
+  // Keeps track of when an extension tried to update itself, so we can throttle
+  // checks to prevent too many requests from being made.
+  std::map<std::string, ThrottleInfo> throttle_info_;
+
   base::WeakPtrFactory<ExtensionUpdater> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(ExtensionUpdater);