Don't set QUIC's write alarm if we are connection flow control blocked.

net/quic/quic_connection.h

Index: net/quic/quic_connection.h
diff --git a/net/quic/quic_connection.h b/net/quic/quic_connection.h
index 50c75ea35b752591b2068a3c5622ee1bef1ba305..8b6e034b5edde5ec3c16cc53ced95c521b756ab9 100644
--- a/net/quic/quic_connection.h
+++ b/net/quic/quic_connection.h
@@ -93,10 +93,12 @@ class NET_EXPORT_PRIVATE QuicConnectionVisitorInterface {
   // Called when a blocked socket becomes writable.
   virtual void OnCanWrite() = 0;
 
-  // Called to ask if any writes are pending in this visitor. Writes may be
-  // pending because they were write-blocked, congestion-throttled or
-  // yielded to other connections.
-  virtual bool HasPendingWrites() const = 0;
+  // Called to ask if the visitor wants to schedule write resumption as it has
+  // both has pending data to write, and is able to write (e.g. based on flow
+  // control limits).
+  // Writes may be pending because they were write-blocked, congestion-throttled
+  // or yielded to other connections.
+  virtual bool WillingAndAbleToWrite() const = 0;
 
   // Called to ask if any handshake messages are pending in this visitor.
   virtual bool HasPendingHandshake() const = 0;