[scheduler] Plumb websocket information to scheduler

third_party/WebKit/Source/platform/WebFrameScheduler.h

Index: third_party/WebKit/Source/platform/WebFrameScheduler.h
diff --git a/third_party/WebKit/Source/platform/WebFrameScheduler.h b/third_party/WebKit/Source/platform/WebFrameScheduler.h
index 069fedf6b2bbc6dd2eac8d1e6ed62e3edc2c383f..a6744ab4a70e2588c033c43554a4b2110a5ecd49 100644
--- a/third_party/WebKit/Source/platform/WebFrameScheduler.h
+++ b/third_party/WebKit/Source/platform/WebFrameScheduler.h
@@ -7,6 +7,8 @@
 
 #include "wtf/RefPtr.h"
 
+#include <memory>
+
 namespace blink {
 
 class WebTaskRunner;
@@ -16,6 +18,15 @@ class WebFrameScheduler {
  public:
   virtual ~WebFrameScheduler() {}
 
+  class ActiveConnectionHandle {

[alex clarke (OOO till 29th), 2017/01/26 16:02:36]

So I like the RAII style handle (we should think about using that pattern
elsewhere), although I'm a little sad we have to do a heap allocation (returning
std::unique_ptr).

Could you add a reset method which just clears the weak ptr in the impl?

[alex clarke (OOO till 29th), 2017/01/26 16:13:56]

Actually that would only work if this wasn't virtual. Can probably ignore.

[altimin, 2017/01/26 16:23:13]

Actually we can do that with move-only types:

class WebFrameSchedulerImpl;

class ActiveConnectionHandle {
   ActiveConnectionHandle(WebFrameSchedulerImpl* frame_scheduler);
   ~ActiveConnectionHandle();
   void reset();
  private:
   base::WeakPtr<WebFrameSchedulerImpl> frame_scheduler_;

   DISALLOW_COPY_AND_ASSIGN(ACH);
};

I don't like that it uses base::WeakPtr from WebFrameScheduler. I'm not sure if
we're allowed to do it.

WDYT about this?

[alex clarke (OOO till 29th), 2017/01/26 16:26:54]

Can use WTF::WeakPtr (which is an alias for base::WeakPtr).  I think I may
changed the task queue voters to do that.

+   public:
+    ActiveConnectionHandle() {}
+    virtual ~ActiveConnectionHandle() {}

[alex clarke (OOO till 29th), 2017/01/26 16:02:36]

Please make this pure virtual.

[altimin, 2017/02/08 15:56:54]

We can't have pure virtual destructors.

+
+   private:
+    DISALLOW_COPY_AND_ASSIGN(ActiveConnectionHandle);
+  };
+
   // The scheduler may throttle tasks associated with offscreen frames.
   virtual void setFrameVisible(bool) {}
 
@@ -67,6 +78,13 @@ class WebFrameScheduler {
   // Tells the scheduler that the first meaningful paint has occured for this
   // frame.
   virtual void onFirstMeaningfulPaint() {}
+
+  // Notifies scheduler that this frame has established an active connection

[Sami, 2017/01/26 15:53:34]

nit: mention that this means real time connections which imply the frame
shouldn't be throttled.

[altimin, 2017/02/08 15:56:54]

Done.

+  // (websocket, webrtc, etc). When connection is closed this handle must
+  // be destroyed.
+  virtual std::unique_ptr<ActiveConnectionHandle> onActiveConnectionCreated() {
+    return nullptr;
+  };
 };
 
 }  // namespace blink