SpdyFramer hooks for parsing and handling PRIORITY frames.

net/spdy/spdy_framer.cc

Index: net/spdy/spdy_framer.cc
diff --git a/net/spdy/spdy_framer.cc b/net/spdy/spdy_framer.cc
index 4049e100f19690be484a625a17e3d6ab5eae6a7b..2e8d6b33bcabcd0a88413efb01427a9333b13640 100644
--- a/net/spdy/spdy_framer.cc
+++ b/net/spdy/spdy_framer.cc
@@ -1789,9 +1789,21 @@ size_t SpdyFramer::ProcessControlFramePayload(const char* data, size_t len) {
         break;
       case PRIORITY: {
           DCHECK_LT(SPDY3, protocol_version());
-          // TODO(hkhalil): Process PRIORITY frames rather than ignore them.
-          reader.Seek(5);
+          uint32 parent_stream_id;
+          uint8 weight;
+          bool exclusive;
+          bool successful_read = true;
+          successful_read = reader.ReadUInt32(&parent_stream_id);
+          DCHECK(successful_read);
+          // Exclusivity is indicated by a single bit flag.
+          exclusive = (parent_stream_id >> 31) != 0;
+          // Zero out the highest-order bit to get the parent stream id.
+          parent_stream_id &= 0x7fffffff;
+          successful_read = reader.ReadUInt8(&weight);
+          DCHECK(successful_read);
           DCHECK(reader.IsDoneReading());
+          visitor_->OnPriority(
+              current_frame_stream_id_, parent_stream_id, weight, exclusive);
         }
         break;
       default:
@@ -2819,6 +2831,24 @@ SpdyFrame* SpdyFramer::SerializeAltSvc(const SpdyAltSvcIR& altsvc) {
   return builder.take();
 }
 
+SpdyFrame* SpdyFramer::SerializePriority(const SpdyPriorityIR& priority) {
+  DCHECK_LT(SPDY3, protocol_version());
+  size_t size = GetPrioritySize();
+
+  SpdyFrameBuilder builder(size, protocol_version());
+  builder.BeginNewFrame(*this, PRIORITY, kNoFlags, priority.stream_id());
+
+  // Make sure the highest-order bit in the parent stream id is zeroed out.
+  uint32 parent_stream_id = priority.parent_stream_id() & 0x7fffffff;
+  uint32 exclusive = priority.exclusive() ? 0x80000000 : 0;
+  // Set the one-bit exclusivity flag.
+  uint32 flag_and_parent_id = parent_stream_id | exclusive;
+  builder.WriteUInt32(flag_and_parent_id);
+  builder.WriteUInt8(priority.weight());
+  DCHECK_EQ(GetPrioritySize(), builder.length());
+  return builder.take();
+}
+
 namespace {
 
 class FrameSerializationVisitor : public SpdyFrameVisitor {
@@ -2870,6 +2900,9 @@ class FrameSerializationVisitor : public SpdyFrameVisitor {
   virtual void VisitAltSvc(const SpdyAltSvcIR& altsvc) OVERRIDE {
     frame_.reset(framer_->SerializeAltSvc(altsvc));
   }
+  virtual void VisitPriority(const SpdyPriorityIR& priority) OVERRIDE {
+    frame_.reset(framer_->SerializePriority(priority));
+  }
 
  private:
   SpdyFramer* framer_;