[net] Change order of RequestPriority to natural: higher > lower

BUG=124683
TEST=./net_unittests


Review URL: http://codereview.chromium.org/10185007

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@133766 0039d316-1c4b-4281-b951-d872f2087c98

21 files changed, 115 insertions, 116 deletions

diff --git a/net/base/host_resolver_impl.cc b/net/base/host_resolver_impl.cc
index 534f3a4..0525459 100644
--- a/net/base/host_resolver_impl.cc
+++ b/net/base/host_resolver_impl.cc
@@ -389,7 +389,7 @@ class PriorityTracker {
   void Add(RequestPriority req_priority) {
     ++total_count_;
     ++counts_[req_priority];
-    if (highest_priority_ > req_priority)
+    if (highest_priority_ < req_priority)
       highest_priority_ = req_priority;
   }
 
@@ -399,14 +399,12 @@ class PriorityTracker {
     --total_count_;
     --counts_[req_priority];
     size_t i;
-    for (i = highest_priority_; i < NUM_PRIORITIES && !counts_[i]; ++i);
+    for (i = highest_priority_; i > MINIMUM_PRIORITY && !counts_[i]; --i);
     highest_priority_ = static_cast<RequestPriority>(i);
 
-    // In absence of requests set default.
-    if (highest_priority_ == NUM_PRIORITIES) {
-      DCHECK_EQ(0u, total_count_);
-      highest_priority_ = IDLE;
-    }
+    // In absence of requests, default to MINIMUM_PRIORITY.
+    if (total_count_ == 0)
+      DCHECK_EQ(MINIMUM_PRIORITY, highest_priority_);
   }
 
  private:
diff --git a/net/base/prioritized_dispatcher.cc b/net/base/prioritized_dispatcher.cc
index afa12f8..9b96e3f 100644
--- a/net/base/prioritized_dispatcher.cc
+++ b/net/base/prioritized_dispatcher.cc
@@ -19,15 +19,15 @@ PrioritizedDispatcher::PrioritizedDispatcher(const Limits& limits)
       max_running_jobs_(limits.reserved_slots.size()),
       num_running_jobs_(0) {
   size_t total = 0;
-  for (size_t i = limits.reserved_slots.size(); i > 0; --i) {
-    total += limits.reserved_slots[i - 1];
-    max_running_jobs_[i - 1] = total;
+  for (size_t i = 0; i < limits.reserved_slots.size(); ++i) {
+    total += limits.reserved_slots[i];
+    max_running_jobs_[i] = total;
   }
   // Unreserved slots are available for all priorities.
   DCHECK_LE(total, limits.total_jobs) << "sum(reserved_slots) <= total_jobs";
   size_t spare = limits.total_jobs - total;
-  for (size_t i = 0; i < max_running_jobs_.size(); ++i) {
-    max_running_jobs_[i] += spare;
+  for (size_t i = limits.reserved_slots.size(); i > 0; --i) {
+    max_running_jobs_[i - 1] += spare;
   }
 }
 
@@ -50,7 +50,7 @@ void PrioritizedDispatcher::Cancel(const Handle& handle) {
 }
 
 PrioritizedDispatcher::Job* PrioritizedDispatcher::EvictOldestLowest() {
-  Handle handle = queue_.FirstMax();
+  Handle handle = queue_.FirstMin();
   if (handle.is_null())
     return NULL;
   Job* job = handle.value();
@@ -78,7 +78,7 @@ PrioritizedDispatcher::Handle PrioritizedDispatcher::ChangePriority(
 void PrioritizedDispatcher::OnJobFinished() {
   DCHECK_GT(num_running_jobs_, 0u);
   --num_running_jobs_;
-  Handle handle = queue_.FirstMin();
+  Handle handle = queue_.FirstMax();
   if (handle.is_null()) {
     DCHECK_EQ(0u, queue_.size());
     return;
diff --git a/net/base/prioritized_dispatcher.h b/net/base/prioritized_dispatcher.h
index c10061b..7e59d4e6 100644
--- a/net/base/prioritized_dispatcher.h
+++ b/net/base/prioritized_dispatcher.h
@@ -13,7 +13,7 @@
 
 namespace net {
 
-// A priority-based dispatcher of jobs. Dispatch order is by priority (lowest
+// A priority-based dispatcher of jobs. Dispatch order is by priority (highest
 // first) and then FIFO. The dispatcher enforces limits on the number of running
 // jobs. It never revokes a job once started. The job must call OnJobFinished
 // once it finishes in order to dispatch further jobs.
@@ -32,7 +32,7 @@ class NET_EXPORT_PRIVATE PrioritizedDispatcher {
   // For example, |total_jobs| = 30 and |reserved_slots| = { 5, 10, 5 }
   // allow for at most 30 running jobs in total. If there are already 24 jobs
   // running, then there can be 6 more jobs started of which at most 1 can be
-  // at priority 1 or 0, but the rest has to be at 0.
+  // at priority 1 or 2, but the rest have to be at 2.
   struct NET_EXPORT_PRIVATE Limits {
     Limits(Priority num_priorities, size_t total_jobs);
     ~Limits();
diff --git a/net/base/prioritized_dispatcher_unittest.cc b/net/base/prioritized_dispatcher_unittest.cc
index ff32003..6c19b92 100644
--- a/net/base/prioritized_dispatcher_unittest.cc
+++ b/net/base/prioritized_dispatcher_unittest.cc
@@ -17,11 +17,12 @@ namespace net {
 namespace {
 
 // We rely on the priority enum values being sequential having starting at 0,
-// and increasing for lower priorities.
-COMPILE_ASSERT(HIGHEST == 0u &&
-               LOWEST > HIGHEST &&
-               IDLE > LOWEST &&
-               NUM_PRIORITIES > IDLE,
+// and increasing for higher priorities.
+COMPILE_ASSERT(MINIMUM_PRIORITY == 0u &&
+               MINIMUM_PRIORITY == IDLE &&
+               IDLE < LOWEST &&
+               LOWEST < HIGHEST &&
+               HIGHEST < NUM_PRIORITIES,
                priority_indexes_incompatible);
 
 class PrioritizedDispatcherTest : public testing::Test {
diff --git a/net/base/request_priority.h b/net/base/request_priority.h
index ca7a1ec..6cf1eef 100644
--- a/net/base/request_priority.h
+++ b/net/base/request_priority.h
@@ -1,4 +1,4 @@
-// Copyright (c) 2009 The Chromium Authors. All rights reserved.
+// Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
@@ -11,11 +11,12 @@ namespace net {
 // Prioritization used in various parts of the networking code such
 // as connection prioritization and resource loading prioritization.
 enum RequestPriority {
-  HIGHEST = 0,   // 0 must be the highest priority.
-  MEDIUM,
-  LOW,
+  MINIMUM_PRIORITY = 0,
+  IDLE = 0,
   LOWEST,
-  IDLE,
+  LOW,
+  MEDIUM,
+  HIGHEST,
   NUM_PRIORITIES,
 };
 
diff --git a/net/http/http_network_transaction.cc b/net/http/http_network_transaction.cc
index 0a88bb8..43df7ce 100644
--- a/net/http/http_network_transaction.cc
+++ b/net/http/http_network_transaction.cc
@@ -1020,10 +1020,10 @@ void HttpNetworkTransaction::LogTransactionConnectedMetrics() {
     }
   }
 
-  // Currently, non-zero priority requests are frame or sub-frame resource
+  // Currently, non-HIGHEST priority requests are frame or sub-frame resource
   // types.  This will change when we also prioritize certain subresources like
   // css, js, etc.
-  if (request_->priority) {
+  if (request_->priority != HIGHEST) {
     UMA_HISTOGRAM_CUSTOM_TIMES(
         "Net.Priority_High_Latency_b",
         total_duration,
diff --git a/net/socket/client_socket_pool_base.cc b/net/socket/client_socket_pool_base.cc
index ab959cf..521436f 100644
--- a/net/socket/client_socket_pool_base.cc
+++ b/net/socket/client_socket_pool_base.cc
@@ -222,7 +222,7 @@ ClientSocketPoolBaseHelper::CallbackResultPair::~CallbackResultPair() {}
 void ClientSocketPoolBaseHelper::InsertRequestIntoQueue(
     const Request* r, RequestQueue* pending_requests) {
   RequestQueue::iterator it = pending_requests->begin();
-  while (it != pending_requests->end() && r->priority() >= (*it)->priority())
+  while (it != pending_requests->end() && r->priority() <= (*it)->priority())
     ++it;
   pending_requests->insert(it, r);
 }
@@ -332,7 +332,6 @@ void ClientSocketPoolBaseHelper::RequestSockets(
 int ClientSocketPoolBaseHelper::RequestSocketInternal(
     const std::string& group_name,
     const Request* request) {
-  DCHECK_GE(request->priority(), 0);
   ClientSocketHandle* const handle = request->handle();
   const bool preconnecting = !handle;
   Group* group = GetOrCreateGroup(group_name);
@@ -834,7 +833,7 @@ bool ClientSocketPoolBaseHelper::FindTopStalledGroup(
         return true;
       has_stalled_group = true;
       bool has_higher_priority = !top_group ||
-          curr_group->TopPendingPriority() < top_group->TopPendingPriority();
+          curr_group->TopPendingPriority() > top_group->TopPendingPriority();
       if (has_higher_priority) {
         top_group = curr_group;
         top_group_name = &i->first;
diff --git a/net/spdy/buffered_spdy_framer.cc b/net/spdy/buffered_spdy_framer.cc
index 1839b52..bc8af33 100644
--- a/net/spdy/buffered_spdy_framer.cc
+++ b/net/spdy/buffered_spdy_framer.cc
@@ -171,7 +171,7 @@ bool BufferedSpdyFramer::HasError() {
 SpdySynStreamControlFrame* BufferedSpdyFramer::CreateSynStream(
     SpdyStreamId stream_id,
     SpdyStreamId associated_stream_id,
-    int priority,
+    SpdyPriority priority,
     uint8 credential_slot,
     SpdyControlFlags flags,
     bool compressed,
diff --git a/net/spdy/buffered_spdy_framer.h b/net/spdy/buffered_spdy_framer.h
index 880f972..b10f46f 100644
--- a/net/spdy/buffered_spdy_framer.h
+++ b/net/spdy/buffered_spdy_framer.h
@@ -110,7 +110,7 @@ class NET_EXPORT_PRIVATE BufferedSpdyFramer
   bool HasError();
   SpdySynStreamControlFrame* CreateSynStream(SpdyStreamId stream_id,
                                              SpdyStreamId associated_stream_id,
-                                             int priority,
+                                             SpdyPriority priority,
                                              uint8 credential_slot,
                                              SpdyControlFlags flags,
                                              bool compressed,
diff --git a/net/spdy/spdy_http_utils.cc b/net/spdy/spdy_http_utils.cc
index f029a99..8a51685 100644
--- a/net/spdy/spdy_http_utils.cc
+++ b/net/spdy/spdy_http_utils.cc
@@ -125,21 +125,25 @@ void CreateSpdyHeadersFromHttpRequest(const HttpRequestInfo& info,
 
 }
 
+COMPILE_ASSERT(HIGHEST - LOWEST < 4 &&
+               HIGHEST - MINIMUM_PRIORITY < 5,
+               request_priority_incompatible_with_spdy);
+
 SpdyPriority ConvertRequestPriorityToSpdyPriority(
     const RequestPriority priority,
     int protocol_version) {
-  DCHECK(HIGHEST <= priority && priority < NUM_PRIORITIES);
+  DCHECK_GE(priority, MINIMUM_PRIORITY);
+  DCHECK_LT(priority, NUM_PRIORITIES);
   if (protocol_version == 2) {
     // SPDY 2 only has 2 bits of priority, but we have 5 RequestPriorities.
-    if (priority < LOWEST) {
-      return priority;
+    // Map IDLE => 3, LOWEST => 2, LOW => 2, MEDIUM => 1, HIGHEST => 0.
+    if (priority > LOWEST) {
+      return static_cast<SpdyPriority>(HIGHEST - priority);
     } else {
-      DCHECK_GE(4, priority);
-      return priority - 1;
+      return static_cast<SpdyPriority>(HIGHEST - priority - 1);
     }
   } else {
-    DCHECK_GE(7, priority);
-    return priority;
+    return static_cast<SpdyPriority>(HIGHEST - priority);
   }
 }
 
diff --git a/net/spdy/spdy_io_buffer.cc b/net/spdy/spdy_io_buffer.cc
index f7120c8..5720f7d 100644
--- a/net/spdy/spdy_io_buffer.cc
+++ b/net/spdy/spdy_io_buffer.cc
@@ -1,4 +1,4 @@
-// Copyright (c) 2009 The Chromium Authors. All rights reserved.
+// Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
@@ -11,13 +11,14 @@ namespace net {
 uint64 SpdyIOBuffer::order_ = 0;
 
 SpdyIOBuffer::SpdyIOBuffer(
-    IOBuffer* buffer, int size, int priority, SpdyStream* stream)
+    IOBuffer* buffer, int size, RequestPriority priority, SpdyStream* stream)
   : buffer_(new DrainableIOBuffer(buffer, size)),
     priority_(priority),
     position_(++order_),
     stream_(stream) {}
 
-SpdyIOBuffer::SpdyIOBuffer() : priority_(0), position_(0), stream_(NULL) {}
+SpdyIOBuffer::SpdyIOBuffer() : priority_(HIGHEST), position_(0), stream_(NULL) {
+}
 
 SpdyIOBuffer::~SpdyIOBuffer() {}
 
diff --git a/net/spdy/spdy_io_buffer.h b/net/spdy/spdy_io_buffer.h
index e96c946..0aaced3 100644
--- a/net/spdy/spdy_io_buffer.h
+++ b/net/spdy/spdy_io_buffer.h
@@ -1,4 +1,4 @@
-// Copyright (c) 2011 The Chromium Authors. All rights reserved.
+// Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
@@ -22,10 +22,10 @@ class NET_EXPORT_PRIVATE SpdyIOBuffer {
   // Constructor
   // |buffer| is the actual data buffer.
   // |size| is the size of the data buffer.
-  // |priority| is the priority of this buffer.  Lower numbers are higher
-  //            priority.
+  // |priority| is the priority of this buffer.
   // |stream| is a pointer to the stream which is managing this buffer.
-  SpdyIOBuffer(IOBuffer* buffer, int size, int priority, SpdyStream* stream);
+  SpdyIOBuffer(IOBuffer* buffer, int size, RequestPriority priority,
+               SpdyStream* stream);
   SpdyIOBuffer();
   ~SpdyIOBuffer();
 
@@ -33,19 +33,19 @@ class NET_EXPORT_PRIVATE SpdyIOBuffer {
   DrainableIOBuffer* buffer() const { return buffer_; }
   size_t size() const { return buffer_->size(); }
   void release();
-  int priority() const { return priority_; }
+  RequestPriority priority() const { return priority_; }
   const scoped_refptr<SpdyStream>& stream() const { return stream_; }
 
   // Comparison operator to support sorting.
   bool operator<(const SpdyIOBuffer& other) const {
     if (priority_ != other.priority_)
-      return priority_ > other.priority_;
+      return priority_ < other.priority_;
     return position_ > other.position_;
   }
 
  private:
   scoped_refptr<DrainableIOBuffer> buffer_;
-  int priority_;
+  RequestPriority priority_;
   uint64 position_;
   scoped_refptr<SpdyStream> stream_;
   static uint64 order_;  // Maintains a FIFO order for equal priorities.
diff --git a/net/spdy/spdy_network_transaction_spdy2_unittest.cc b/net/spdy/spdy_network_transaction_spdy2_unittest.cc
index 6b402b6..978e35e 100644
--- a/net/spdy/spdy_network_transaction_spdy2_unittest.cc
+++ b/net/spdy/spdy_network_transaction_spdy2_unittest.cc
@@ -567,8 +567,8 @@ TEST_P(SpdyNetworkTransactionSpdy2Test, Get) {
 }
 
 TEST_P(SpdyNetworkTransactionSpdy2Test, GetAtEachPriority) {
-  for (RequestPriority p = HIGHEST; p < NUM_PRIORITIES;
-       p = RequestPriority(p+1)) {
+  for (RequestPriority p = MINIMUM_PRIORITY; p < NUM_PRIORITIES;
+       p = RequestPriority(p + 1)) {
     // Construct the request.
     scoped_ptr<SpdyFrame> req(ConstructSpdyGet(NULL, 0, false, 1, p));
     MockWrite writes[] = { CreateMockWrite(*req) };
diff --git a/net/spdy/spdy_network_transaction_spdy3_unittest.cc b/net/spdy/spdy_network_transaction_spdy3_unittest.cc
index dcc48e5..6cfe4a6 100644
--- a/net/spdy/spdy_network_transaction_spdy3_unittest.cc
+++ b/net/spdy/spdy_network_transaction_spdy3_unittest.cc
@@ -569,8 +569,8 @@ TEST_P(SpdyNetworkTransactionSpdy3Test, Get) {
 }
 
 TEST_P(SpdyNetworkTransactionSpdy3Test, GetAtEachPriority) {
-  for (RequestPriority p = HIGHEST; p < NUM_PRIORITIES;
-       p = RequestPriority(p+1)) {
+  for (RequestPriority p = MINIMUM_PRIORITY; p < NUM_PRIORITIES;
+       p = RequestPriority(p + 1)) {
     // Construct the request.
     scoped_ptr<SpdyFrame> req(ConstructSpdyGet(NULL, 0, false, 1, p));
     MockWrite writes[] = { CreateMockWrite(*req) };
diff --git a/net/spdy/spdy_session.cc b/net/spdy/spdy_session.cc
index 278fa25..4f2ac3a 100644
--- a/net/spdy/spdy_session.cc
+++ b/net/spdy/spdy_session.cc
@@ -535,7 +535,7 @@ void SpdySession::ProcessPendingCreateStreams() {
   while (!max_concurrent_streams_ ||
          active_streams_.size() < max_concurrent_streams_) {
     bool no_pending_create_streams = true;
-    for (int i = 0;i < NUM_PRIORITIES;++i) {
+    for (int i = NUM_PRIORITIES - 1; i >= MINIMUM_PRIORITY; --i) {
       if (!create_stream_queues_[i].empty()) {
         PendingCreateStream pending_create = create_stream_queues_[i].front();
         create_stream_queues_[i].pop();
@@ -568,7 +568,7 @@ void SpdySession::CancelPendingCreateStreams(
     return;
   }
 
-  for (int i = 0;i < NUM_PRIORITIES;++i) {
+  for (int i = 0; i < NUM_PRIORITIES; ++i) {
     PendingCreateStreamQueue tmp;
     // Make a copy removing this trans
     while (!create_stream_queues_[i].empty()) {
@@ -590,6 +590,9 @@ int SpdySession::CreateStreamImpl(
     RequestPriority priority,
     scoped_refptr<SpdyStream>* spdy_stream,
     const BoundNetLog& stream_net_log) {
+  DCHECK_GE(priority, MINIMUM_PRIORITY);
+  DCHECK_LT(priority, NUM_PRIORITIES);
+
   // Make sure that we don't try to send https/wss over an unauthenticated, but
   // encrypted SSL socket.
   if (is_secure_ && certificate_error_code_ != OK &&
@@ -622,7 +625,6 @@ int SpdySession::CreateStreamImpl(
       static_cast<int>(priority), 0, 10, 11);
 
   // TODO(mbelshe): Optimize memory allocations
-  DCHECK(priority >= net::HIGHEST && priority < net::NUM_PRIORITIES);
 
   DCHECK_EQ(active_streams_[stream_id].get(), stream.get());
   return OK;
@@ -834,7 +836,7 @@ void SpdySession::ResetStream(SpdyStreamId stream_id,
       buffered_spdy_framer_->CreateRstStream(stream_id, status));
 
   // Default to lowest priority unless we know otherwise.
-  int priority = 3;
+  RequestPriority priority = net::IDLE;
   if(IsStreamActive(stream_id)) {
     scoped_refptr<SpdyStream> stream = active_streams_[stream_id];
     priority = stream->priority();
@@ -1054,7 +1056,8 @@ void SpdySession::WriteSocket() {
         memcpy(buffer->data(), compressed_frame->data(), size);
 
         // Attempt to send the frame.
-        in_flight_write_ = SpdyIOBuffer(buffer, size, 0, next_buffer.stream());
+        in_flight_write_ = SpdyIOBuffer(buffer, size, HIGHEST,
+                                        next_buffer.stream());
       } else {
         size = uncompressed_frame.length() + SpdyFrame::kHeaderSize;
         in_flight_write_ = next_buffer;
@@ -1094,7 +1097,7 @@ void SpdySession::CloseAllStreams(net::Error status) {
     unclaimed_pushed_streams_.clear();
   }
 
-  for (int i = 0;i < NUM_PRIORITIES;++i) {
+  for (int i = 0; i < NUM_PRIORITIES; ++i) {
     while (!create_stream_queues_[i].empty()) {
       PendingCreateStream pending_create = create_stream_queues_[i].front();
       create_stream_queues_[i].pop();
@@ -1126,7 +1129,7 @@ int SpdySession::GetNewStreamId() {
 }
 
 void SpdySession::QueueFrame(SpdyFrame* frame,
-                             SpdyPriority priority,
+                             RequestPriority priority,
                              SpdyStream* stream) {
   int length = SpdyFrame::kHeaderSize + frame->length();
   IOBuffer* buffer = new IOBuffer(length);
@@ -1741,7 +1744,7 @@ void SpdySession::SendSettings() {
   scoped_ptr<SpdySettingsControlFrame> settings_frame(
       buffered_spdy_framer_->CreateSettings(settings_map_new));
   sent_settings_ = true;
-  QueueFrame(settings_frame.get(), 0, NULL);
+  QueueFrame(settings_frame.get(), HIGHEST, NULL);
 }
 
 void SpdySession::HandleSetting(uint32 id, uint32 value) {
@@ -1818,8 +1821,7 @@ void SpdySession::WritePingFrame(uint32 unique_id) {
   DCHECK(buffered_spdy_framer_.get());
   scoped_ptr<SpdyPingControlFrame> ping_frame(
       buffered_spdy_framer_->CreatePingFrame(next_ping_id_));
-  QueueFrame(
-      ping_frame.get(), buffered_spdy_framer_->GetHighestPriority(), NULL);
+  QueueFrame(ping_frame.get(), HIGHEST, NULL);
 
   if (net_log().IsLoggingAllEvents()) {
     net_log().AddEvent(
diff --git a/net/spdy/spdy_session.h b/net/spdy/spdy_session.h
index 68a1a42..7b93171 100644
--- a/net/spdy/spdy_session.h
+++ b/net/spdy/spdy_session.h
@@ -397,7 +397,7 @@ class NET_EXPORT SpdySession : public base::RefCounted<SpdySession>,
   // |frame| is the frame to send.
   // |priority| is the priority for insertion into the queue.
   // |stream| is the stream which this IO is associated with (or NULL).
-  void QueueFrame(SpdyFrame* frame, SpdyPriority priority,
+  void QueueFrame(SpdyFrame* frame, RequestPriority priority,
                   SpdyStream* stream);
 
   // Track active streams in the active stream list.
diff --git a/net/spdy/spdy_session_spdy2_unittest.cc b/net/spdy/spdy_session_spdy2_unittest.cc
index 8afbed2..a4afe3a 100644
--- a/net/spdy/spdy_session_spdy2_unittest.cc
+++ b/net/spdy/spdy_session_spdy2_unittest.cc
@@ -74,36 +74,32 @@ TEST_F(SpdySessionSpdy2Test, SpdyIOBuffer) {
   std::priority_queue<SpdyIOBuffer> queue_;
   const size_t kQueueSize = 100;
 
-  // Insert 100 items; pri 100 to 1.
+  // Insert items with random priority and increasing buffer size.
   for (size_t index = 0; index < kQueueSize; ++index) {
-    SpdyIOBuffer buffer(new IOBuffer(), 0, kQueueSize - index, NULL);
-    queue_.push(buffer);
+    queue_.push(SpdyIOBuffer(
+        new IOBufferWithSize(index + 1),
+        index + 1,
+        static_cast<RequestPriority>(rand() % NUM_PRIORITIES),
+        NULL));
   }
 
-  // Insert several priority 0 items last.
-  const size_t kNumDuplicates = 12;
-  IOBufferWithSize* buffers[kNumDuplicates];
-  for (size_t index = 0; index < kNumDuplicates; ++index) {
-    buffers[index] = new IOBufferWithSize(index+1);
-    queue_.push(SpdyIOBuffer(buffers[index], buffers[index]->size(), 0, NULL));
-  }
-
-  EXPECT_EQ(kQueueSize + kNumDuplicates, queue_.size());
+  EXPECT_EQ(kQueueSize, queue_.size());
 
-  // Verify the P0 items come out in FIFO order.
-  for (size_t index = 0; index < kNumDuplicates; ++index) {
+  // Verify items come out with decreasing priority or FIFO order.
+  RequestPriority last_priority = NUM_PRIORITIES;
+  size_t last_size = 0;
+  for (size_t index = 0; index < kQueueSize; ++index) {
     SpdyIOBuffer buffer = queue_.top();
-    EXPECT_EQ(0, buffer.priority());
-    EXPECT_EQ(index + 1, buffer.size());
+    EXPECT_LE(buffer.priority(), last_priority);
+    if (buffer.priority() < last_priority)
+      last_size = 0;
+    EXPECT_LT(last_size, buffer.size());
+    last_priority = buffer.priority();
+    last_size = buffer.size();
     queue_.pop();
   }
 
-  int priority = 1;
-  while (queue_.size()) {
-    SpdyIOBuffer buffer = queue_.top();
-    EXPECT_EQ(priority++, buffer.priority());
-    queue_.pop();
-  }
+  EXPECT_EQ(0u, queue_.size());
 }
 
 TEST_F(SpdySessionSpdy2Test, GoAway) {
diff --git a/net/spdy/spdy_session_spdy3_unittest.cc b/net/spdy/spdy_session_spdy3_unittest.cc
index 3e53ab2..7ac41c3 100644
--- a/net/spdy/spdy_session_spdy3_unittest.cc
+++ b/net/spdy/spdy_session_spdy3_unittest.cc
@@ -74,36 +74,32 @@ TEST_F(SpdySessionSpdy3Test, SpdyIOBuffer) {
   std::priority_queue<SpdyIOBuffer> queue_;
   const size_t kQueueSize = 100;
 
-  // Insert 100 items; pri 100 to 1.
+  // Insert items with random priority and increasing buffer size
   for (size_t index = 0; index < kQueueSize; ++index) {
-    SpdyIOBuffer buffer(new IOBuffer(), 0, kQueueSize - index, NULL);
-    queue_.push(buffer);
+    queue_.push(SpdyIOBuffer(
+        new IOBufferWithSize(index + 1),
+        index + 1,
+        static_cast<RequestPriority>(rand() % NUM_PRIORITIES),
+        NULL));
   }
 
-  // Insert several priority 0 items last.
-  const size_t kNumDuplicates = 12;
-  IOBufferWithSize* buffers[kNumDuplicates];
-  for (size_t index = 0; index < kNumDuplicates; ++index) {
-    buffers[index] = new IOBufferWithSize(index+1);
-    queue_.push(SpdyIOBuffer(buffers[index], buffers[index]->size(), 0, NULL));
-  }
-
-  EXPECT_EQ(kQueueSize + kNumDuplicates, queue_.size());
+  EXPECT_EQ(kQueueSize, queue_.size());
 
-  // Verify the P0 items come out in FIFO order.
-  for (size_t index = 0; index < kNumDuplicates; ++index) {
+  // Verify items come out with decreasing priority or FIFO order.
+  RequestPriority last_priority = NUM_PRIORITIES;
+  size_t last_size = 0;
+  for (size_t index = 0; index < kQueueSize; ++index) {
     SpdyIOBuffer buffer = queue_.top();
-    EXPECT_EQ(0, buffer.priority());
-    EXPECT_EQ(index + 1, buffer.size());
+    EXPECT_LE(buffer.priority(), last_priority);
+    if (buffer.priority() < last_priority)
+      last_size = 0;
+    EXPECT_LT(last_size, buffer.size());
+    last_priority = buffer.priority();
+    last_size = buffer.size();
     queue_.pop();
   }
 
-  int priority = 1;
-  while (queue_.size()) {
-    SpdyIOBuffer buffer = queue_.top();
-    EXPECT_EQ(priority++, buffer.priority());
-    queue_.pop();
-  }
+  EXPECT_EQ(0u, queue_.size());
 }
 
 TEST_F(SpdySessionSpdy3Test, GoAway) {
diff --git a/net/spdy/spdy_stream.cc b/net/spdy/spdy_stream.cc
index c8238fc..154cb27 100644
--- a/net/spdy/spdy_stream.cc
+++ b/net/spdy/spdy_stream.cc
@@ -73,7 +73,7 @@ SpdyStream::SpdyStream(SpdySession* session,
                        const BoundNetLog& net_log)
     : continue_buffering_data_(true),
       stream_id_(stream_id),
-      priority_(0),
+      priority_(HIGHEST),
       slot_(0),
       stalled_by_flow_control_(false),
       send_window_size_(kSpdyStreamInitialWindowSize),
@@ -663,7 +663,7 @@ int SpdyStream::DoSendDomainBoundCert() {
   origin.erase(origin.length() - 1);  // trim trailing slash
   int rv =  session_->WriteCredentialFrame(
       origin, domain_bound_cert_type_, domain_bound_private_key_,
-      domain_bound_cert_, static_cast<RequestPriority>(priority_));
+      domain_bound_cert_, priority_);
   if (rv != ERR_IO_PENDING)
     return rv;
   return OK;
@@ -686,7 +686,7 @@ int SpdyStream::DoSendHeaders() {
 
   CHECK(request_.get());
   int result = session_->WriteSynStream(
-      stream_id_, static_cast<RequestPriority>(priority_), slot_, flags,
+      stream_id_, priority_, slot_, flags,
       request_);
   if (result != ERR_IO_PENDING)
     return result;
diff --git a/net/spdy/spdy_stream.h b/net/spdy/spdy_stream.h
index 55e8777..5f5ceda 100644
--- a/net/spdy/spdy_stream.h
+++ b/net/spdy/spdy_stream.h
@@ -18,6 +18,7 @@
 #include "net/base/io_buffer.h"
 #include "net/base/net_export.h"
 #include "net/base/net_log.h"
+#include "net/base/request_priority.h"
 #include "net/base/server_bound_cert_service.h"
 #include "net/base/ssl_client_cert_type.h"
 #include "net/base/upload_data.h"
@@ -122,8 +123,8 @@ class NET_EXPORT_PRIVATE SpdyStream
   const std::string& path() const { return path_; }
   void set_path(const std::string& path) { path_ = path; }
 
-  int priority() const { return priority_; }
-  void set_priority(int priority) { priority_ = priority; }
+  RequestPriority priority() const { return priority_; }
+  void set_priority(RequestPriority priority) { priority_ = priority; }
 
   int32 send_window_size() const { return send_window_size_; }
   void set_send_window_size(int32 window_size) {
@@ -315,7 +316,7 @@ class NET_EXPORT_PRIVATE SpdyStream
 
   SpdyStreamId stream_id_;
   std::string path_;
-  int priority_;
+  RequestPriority priority_;
   size_t slot_;
 
   // Flow control variables.
diff --git a/net/url_request/url_request.h b/net/url_request/url_request.h
index d73d2fe..ab7e3e1 100644
--- a/net/url_request/url_request.h
+++ b/net/url_request/url_request.h
@@ -572,7 +572,7 @@ class NET_EXPORT URLRequest : NON_EXPORTED_BASE(public base::NonThreadSafe),
   // Returns the priority level for this request.
   RequestPriority priority() const { return priority_; }
   void set_priority(RequestPriority priority) {
-    DCHECK_GE(priority, HIGHEST);
+    DCHECK_GE(priority, MINIMUM_PRIORITY);
     DCHECK_LT(priority, NUM_PRIORITIES);
     priority_ = priority;
   }