Componentize component_updater: Split content::ResourceThrottle from CUS.

chrome/browser/component_updater/component_updater_service.h

Index: chrome/browser/component_updater/component_updater_service.h
diff --git a/chrome/browser/component_updater/component_updater_service.h b/chrome/browser/component_updater/component_updater_service.h
index 6dec6016c6b239a6f139ccab0d623263b7efa6f8..665ed65dbfcbaca586d64d316ab97269101ac515 100644
--- a/chrome/browser/component_updater/component_updater_service.h
+++ b/chrome/browser/component_updater/component_updater_service.h
@@ -8,6 +8,7 @@
 #include <string>
 #include <vector>
 
+#include "base/callback_forward.h"
 #include "base/gtest_prod_util.h"
 #include "base/memory/ref_counted.h"
 #include "base/version.h"
@@ -171,6 +172,16 @@ class ComponentUpdateService {
   // proactively triggered outside the normal component update service schedule.
   virtual OnDemandUpdater& GetOnDemandUpdater() = 0;
 
+  // |callback| is called on the main thread once the component with |crx_id|
+  // is downloaded and installed. |callback| may be called synchronously

[Sorin Jianu, 2014/08/01 00:03:06]

We need to better document the intention and the functionality of the
|callback|.

[tommycli, 2014/08/05 21:30:25]

I rewrote parts of the comment. It's a bit long now, Let me know what changes to
make...

After writing the comment, I feel like we should rename this method.

+  // if component is already installed. The function implements a cooldown
+  // interval of 30 minutes. That means it will ineffective to call the
+  // function before the cooldown interval has passed. This behavior is intended
+  // to be defensive against programming bugs, usually triggered by web fetches,
+  // where the on-demand functionality is invoked too often.
+  virtual void MaybeThrottle(const std::string& crx_id,
+                             const base::Closure& callback) = 0;
+
   // Returns a task runner suitable for use by component installers.
   virtual scoped_refptr<base::SequencedTaskRunner> GetSequencedTaskRunner() = 0;
 
@@ -183,7 +194,6 @@ class ComponentUpdateService {
                                    CrxUpdateItem* item) const = 0;
 
   friend class ::ComponentsUI;
-  FRIEND_TEST_ALL_PREFIXES(ComponentUpdaterTest, ResourceThrottleLiveNoUpdate);
 };
 
 typedef ComponentUpdateService::Observer ServiceObserver;
@@ -192,17 +202,6 @@ class OnDemandUpdater {
  public:
   virtual ~OnDemandUpdater() {}
 
-  // Returns a network resource throttle. It means that a component will be
-  // downloaded and installed before the resource is unthrottled. This function
-  // can be called from the IO thread. The function implements a cooldown
-  // interval of 30 minutes. That means it will ineffective to call the
-  // function before the cooldown interval has passed. This behavior is intended
-  // to be defensive against programming bugs, usually triggered by web fetches,
-  // where the on-demand functionality is invoked too often.
-  virtual content::ResourceThrottle* GetOnDemandResourceThrottle(
-      net::URLRequest* request,
-      const std::string& crx_id) = 0;
-
  private:
   friend class OnDemandTester;
   friend class ::ComponentsUI;