Deliver webrtc-internals updates in bulk, every 500ms at most.

content/browser/media/webrtc_internals.h

Index: content/browser/media/webrtc_internals.h
diff --git a/content/browser/media/webrtc_internals.h b/content/browser/media/webrtc_internals.h
index f6470008dd45937dcb0e016db8528ae58cc6e367..cbec2334cabcfc772ba6ab01f8bb19f42196e2c4 100644
--- a/content/browser/media/webrtc_internals.h
+++ b/content/browser/media/webrtc_internals.h
@@ -5,10 +5,13 @@
 #ifndef CONTENT_BROWSER_MEDIA_WEBRTC_INTERNALS_H_
 #define CONTENT_BROWSER_MEDIA_WEBRTC_INTERNALS_H_
 
+#include <queue>
+
 #include "base/containers/hash_tables.h"
 #include "base/gtest_prod_util.h"
 #include "base/lazy_instance.h"
 #include "base/memory/scoped_ptr.h"
+#include "base/memory/weak_ptr.h"
 #include "base/observer_list.h"
 #include "base/process/process.h"
 #include "base/values.h"
@@ -81,8 +84,8 @@ class CONTENT_EXPORT WebRTCInternals : public RenderProcessHostObserver,
                       const std::string& video_constraints);
 
   // Methods for adding or removing WebRTCInternalsUIObserver.
-  void AddObserver(WebRTCInternalsUIObserver *observer);
-  void RemoveObserver(WebRTCInternalsUIObserver *observer);
+  void AddObserver(WebRTCInternalsUIObserver* observer);
+  void RemoveObserver(WebRTCInternalsUIObserver* observer);
 
   // Sends all update data to |observer|.
   void UpdateObserver(WebRTCInternalsUIObserver* observer);
@@ -116,7 +119,7 @@ class CONTENT_EXPORT WebRTCInternals : public RenderProcessHostObserver,
   WebRTCInternals();
   ~WebRTCInternals() override;
 
-  void SendUpdate(const std::string& command, base::Value* value);
+  void SendUpdate(const std::string& command, scoped_ptr<base::Value> value);
 
   // RenderProcessHostObserver implementation.
   void RenderProcessHostDestroyed(RenderProcessHost* host) override;
@@ -145,6 +148,12 @@ class CONTENT_EXPORT WebRTCInternals : public RenderProcessHostObserver,
   // application for power-saving.
   void CreateOrReleasePowerSaveBlocker();
 
+  // Called on a timer to deliver updates to javascript.
+  // We throttle and bulk together updates to avoid DOS like scenarios where
+  // a page uses a lot of peerconnection instances with many event
+  // notifications.
+  void ProcessPendingUpdates();
+
   base::ObserverList<WebRTCInternalsUIObserver> observers_;
 
   // |peer_connection_data_| is a list containing all the PeerConnection
@@ -191,6 +200,27 @@ class CONTENT_EXPORT WebRTCInternals : public RenderProcessHostObserver,
 
   // Set of render process hosts that |this| is registered as an observer on.
   base::hash_set<int> render_process_id_set_;
+
+  class PendingUpdate {

[Henrik Grunell, 2016/02/08 09:52:08]

Comment on the new class and variables. Threading.

[Henrik Grunell, 2016/02/09 08:18:11]

Not addressed yet. I think it's good to have, especially around the queuing and
flag required. 

[tommi (sloooow) - chröme, 2016/02/09 09:34:16]

Done.  I added documentation for the class that mentions the state that it holds
and with that information I think the variables are otherwise self explanatory. 
Also added a thread checker.

+   public:
+    PendingUpdate(const std::string& command, scoped_ptr<base::Value> value);
+    PendingUpdate(PendingUpdate&& other);
+    ~PendingUpdate();
+
+    const std::string& command() const { return command_; }
+    const base::Value* value() const { return value_.get(); }
+
+   private:
+    std::string command_;
+    scoped_ptr<base::Value> value_;
+    DISALLOW_COPY_AND_ASSIGN(PendingUpdate);
+  };
+
+  bool pending_updates_queued_;
+  std::queue<PendingUpdate> pending_updates_;
+
+  // Weak factory for this object that we use for bulking up updates.
+  base::WeakPtrFactory<WebRTCInternals> weak_factory_;
 };
 
 }  // namespace content