Fix bug in net::RequestPriority -> HTTP/2 dependency conversion.

This CL also defaults this behavior on (subject to finch override), refactors the finch control to be in line with network stack defaults (== based in io_thread.cc),  and removes the non-default performance bot configuration.

BUG=590225
R=bnc@chromium.org
R=isherman@chromium.org

Review URL: https://codereview.chromium.org/1779733003

Cr-Commit-Position: refs/heads/master@{#382360}

31 files changed, 363 insertions, 136 deletions

diff --git a/chrome/browser/io_thread.cc b/chrome/browser/io_thread.cc
index 1e1979b..f8e9b01 100644
--- a/chrome/browser/io_thread.cc
+++ b/chrome/browser/io_thread.cc
@@ -180,6 +180,11 @@ const char kNpnTrialName[] = "NPN";
 const char kNpnTrialEnabledGroupNamePrefix[] = "Enable";
 const char kNpnTrialDisabledGroupNamePrefix[] = "Disable";
 
+// Field trial for priority dependencies.
+const char kSpdyDependenciesFieldTrial[] = "SpdyEnableDependencies";
+const char kSpdyDependenciesFieldTrialEnable[] = "Enable";
+const char kSpdyDepencenciesFieldTrialDisable[] = "Disable";
+
 #if defined(OS_MACOSX)
 void ObserveKeychainEvents() {
   DCHECK_CURRENTLY_ON(BrowserThread::UI);
@@ -802,6 +807,7 @@ void IOThread::Init() {
           switches::kEnableUserAlternateProtocolPorts)) {
     globals_->enable_user_alternate_protocol_ports = true;
   }
+  ConfigurePriorityDependencies();
   globals_->enable_brotli.set(
       base::FeatureList::IsEnabled(features::kBrotliEncoding));
   globals_->enable_token_binding =
@@ -1102,6 +1108,9 @@ void IOThread::InitializeNetworkSessionParamsFromGlobals(
 
   globals.enable_brotli.CopyToIfSet(&params->enable_brotli);
 
+  globals.enable_priority_dependencies.CopyToIfSet(
+      &params->enable_priority_dependencies);
+
   globals.enable_quic.CopyToIfSet(&params->enable_quic);
   globals.disable_quic_on_timeout_with_open_streams.CopyToIfSet(
     &params->disable_quic_on_timeout_with_open_streams);
@@ -1208,6 +1217,16 @@ void IOThread::UpdateDnsClientEnabled() {
   globals()->host_resolver->SetDnsClientEnabled(*dns_client_enabled_);
 }
 
+void IOThread::ConfigurePriorityDependencies() {
+  std::string group =
+      base::FieldTrialList::FindFullName(kSpdyDependenciesFieldTrial);
+  if (group == kSpdyDependenciesFieldTrialEnable) {
+    globals_->enable_priority_dependencies.set(true);
+  } else if (group == kSpdyDepencenciesFieldTrialDisable) {
+    globals_->enable_priority_dependencies.set(false);
+  }
+}
+
 void IOThread::ConfigureQuic(const base::CommandLine& command_line) {
   // Always fetch the field trial group to ensure it is reported correctly.
   // The command line flags will be associated with a group that is reported
diff --git a/chrome/browser/io_thread.h b/chrome/browser/io_thread.h
index d21ce61..6cb2e07 100644
--- a/chrome/browser/io_thread.h
+++ b/chrome/browser/io_thread.h
@@ -215,6 +215,8 @@ class IOThread : public content::BrowserThreadDelegate {
 
     Optional<bool> enable_brotli;
 
+    Optional<bool> enable_priority_dependencies;
+
     Optional<bool> enable_quic;
     Optional<bool> disable_quic_on_timeout_with_open_streams;
     Optional<bool> enable_quic_for_proxies;
@@ -356,6 +358,9 @@ class IOThread : public content::BrowserThreadDelegate {
   void UpdateNegotiateDisableCnameLookup();
   void UpdateNegotiateEnablePort();
 
+  // Configure the use of priority dependencies in SPDY/HTTP2
+  void ConfigurePriorityDependencies();
+
   // Configures QUIC options based on the flags in |command_line| as
   // well as the QUIC field trial group.
   void ConfigureQuic(const base::CommandLine& command_line);
diff --git a/ios/chrome/browser/ios_chrome_io_thread.h b/ios/chrome/browser/ios_chrome_io_thread.h
index 17c7faa..34d4507 100644
--- a/ios/chrome/browser/ios_chrome_io_thread.h
+++ b/ios/chrome/browser/ios_chrome_io_thread.h
@@ -141,6 +141,8 @@ class IOSChromeIOThread : public web::WebThreadDelegate {
 
     Optional<bool> enable_npn;
 
+    Optional<bool> enable_priority_dependencies;
+
     Optional<bool> enable_quic;
     Optional<bool> enable_quic_for_proxies;
     Optional<bool> quic_always_require_handshake_confirmation;
@@ -252,6 +254,10 @@ class IOSChromeIOThread : public web::WebThreadDelegate {
 
   void ChangedToOnTheRecordOnIOThread();
 
+  // Configure whether we set HTTP/2 dependencies from the
+  // net::RequestPriority.
+  void ConfigurePriorityDependencies();
+
   // Configures QUIC options based on the QUIC field trial group.
   void ConfigureQuic();
 
diff --git a/ios/chrome/browser/ios_chrome_io_thread.mm b/ios/chrome/browser/ios_chrome_io_thread.mm
index 4e76c5a..1cd36da 100644
--- a/ios/chrome/browser/ios_chrome_io_thread.mm
+++ b/ios/chrome/browser/ios_chrome_io_thread.mm
@@ -137,6 +137,11 @@ const char kNpnTrialName[] = "NPN";
 const char kNpnTrialEnabledGroupNamePrefix[] = "Enable";
 const char kNpnTrialDisabledGroupNamePrefix[] = "Disable";
 
+// Field trial for priority dependencies.
+const char kSpdyDependenciesFieldTrial[] = "SpdyEnableDependencies";
+const char kSpdyDependenciesFieldTrialEnable[] = "Enable";
+const char kSpdyDepencenciesFieldTrialDisable[] = "Disable";
+
 // Used for the "system" URLRequestContext.
 class SystemURLRequestContext : public net::URLRequestContext {
  public:
@@ -455,6 +460,7 @@ void IOSChromeIOThread::Init() {
   ConfigureAltSvcGlobals(
       base::FieldTrialList::FindFullName(kAltSvcFieldTrialName), globals_);
   ConfigureQuic();
+  ConfigurePriorityDependencies();
   InitializeNetworkOptions();
 
   const version_info::Channel channel = ::GetChannel();
@@ -647,6 +653,9 @@ void IOSChromeIOThread::InitializeNetworkSessionParamsFromGlobals(
 
   globals.enable_npn.CopyToIfSet(&params->enable_npn);
 
+  globals.enable_priority_dependencies.CopyToIfSet(
+      &params->enable_priority_dependencies);
+
   globals.enable_quic.CopyToIfSet(&params->enable_quic);
   globals.enable_quic_for_proxies.CopyToIfSet(&params->enable_quic_for_proxies);
   globals.quic_always_require_handshake_confirmation.CopyToIfSet(
@@ -727,6 +736,16 @@ void IOSChromeIOThread::InitSystemRequestContextOnIOThread() {
       ConstructSystemRequestContext(globals_, net_log_));
 }
 
+void IOSChromeIOThread::ConfigurePriorityDependencies() {
+  std::string group =
+      base::FieldTrialList::FindFullName(kSpdyDependenciesFieldTrial);
+  if (group == kSpdyDependenciesFieldTrialEnable) {
+    globals_->enable_priority_dependencies.set(true);
+  } else if (group == kSpdyDepencenciesFieldTrialDisable) {
+    globals_->enable_priority_dependencies.set(false);
+  }
+}
+
 void IOSChromeIOThread::ConfigureQuic() {
   // Always fetch the field trial group to ensure it is reported correctly.
   // The command line flags will be associated with a group that is reported
diff --git a/net/http/bidirectional_stream_unittest.cc b/net/http/bidirectional_stream_unittest.cc
index 6658d82..a3bc810 100644
--- a/net/http/bidirectional_stream_unittest.cc
+++ b/net/http/bidirectional_stream_unittest.cc
@@ -296,7 +296,7 @@ class MockTimer : public base::MockTimer {
 class BidirectionalStreamTest : public testing::TestWithParam<bool> {
  public:
   BidirectionalStreamTest()
-      : spdy_util_(kProtoHTTP2, false),
+      : spdy_util_(kProtoHTTP2, true),
         session_deps_(kProtoHTTP2),
         ssl_data_(SSLSocketDataProvider(ASYNC, OK)) {
     ssl_data_.SetNextProto(kProtoHTTP2);
diff --git a/net/http/http_network_session.cc b/net/http/http_network_session.cc
index da649b0..053509a 100644
--- a/net/http/http_network_session.cc
+++ b/net/http/http_network_session.cc
@@ -99,6 +99,7 @@ HttpNetworkSession::Params::Params()
       enable_alternative_service_with_different_host(false),
       enable_npn(true),
       enable_brotli(false),
+      enable_priority_dependencies(true),
       enable_quic(false),
       disable_quic_on_timeout_with_open_streams(false),
       enable_quic_for_proxies(false),
@@ -193,6 +194,7 @@ HttpNetworkSession::HttpNetworkSession(const Params& params)
                          params.http_server_properties,
                          params.transport_security_state,
                          params.enable_spdy_ping_based_connection_checking,
+                         params.enable_priority_dependencies,
                          params.spdy_default_protocol,
                          params.spdy_session_max_recv_window_size,
                          params.spdy_stream_max_recv_window_size,
diff --git a/net/http/http_network_session.h b/net/http/http_network_session.h
index 094eea8..a636308 100644
--- a/net/http/http_network_session.h
+++ b/net/http/http_network_session.h
@@ -106,6 +106,9 @@ class NET_EXPORT HttpNetworkSession
     // Enables Brotli Content-Encoding support.
     bool enable_brotli;
 
+    // Enable setting of HTTP/2 dependencies based on priority.
+    bool enable_priority_dependencies;
+
     // Enables QUIC support.
     bool enable_quic;
     // Disable QUIC if a connection times out with open streams.
diff --git a/net/http/http_network_transaction_unittest.cc b/net/http/http_network_transaction_unittest.cc
index b44bf3b..2cf63e4 100644
--- a/net/http/http_network_transaction_unittest.cc
+++ b/net/http/http_network_transaction_unittest.cc
@@ -271,7 +271,6 @@ class HttpNetworkTransactionTest
         HttpNetworkSession::NORMAL_SOCKET_POOL, old_max_pool_sockets_);
     ClientSocketPoolManager::set_max_sockets_per_group(
         HttpNetworkSession::NORMAL_SOCKET_POOL, old_max_group_sockets_);
-    SpdySession::SetPriorityDependencyDefaultForTesting(false);
   }
 
  protected:
@@ -282,8 +281,7 @@ class HttpNetworkTransactionTest
             HttpNetworkSession::NORMAL_SOCKET_POOL)),
         old_max_pool_sockets_(ClientSocketPoolManager::max_sockets_per_pool(
             HttpNetworkSession::NORMAL_SOCKET_POOL)) {
-    SpdySession::SetPriorityDependencyDefaultForTesting(
-        GetDependenciesFromPriority());
+    session_deps_.enable_priority_dependencies = GetDependenciesFromPriority();
   }
 
   struct SimpleGetHelperResult {
diff --git a/net/http/http_proxy_client_socket_pool_unittest.cc b/net/http/http_proxy_client_socket_pool_unittest.cc
index 29c10d0..7fea5f1 100644
--- a/net/http/http_proxy_client_socket_pool_unittest.cc
+++ b/net/http/http_proxy_client_socket_pool_unittest.cc
@@ -86,20 +86,18 @@ class HttpProxyClientSocketPoolTest
                          NULL,
                          session_deps_.ssl_config_service.get(),
                          BoundNetLog().net_log()),
-        session_(CreateNetworkSession()),
         spdy_util_(GetParam().protocol, GetParam().priority_to_dependency),
         pool_(kMaxSockets,
               kMaxSocketsPerGroup,
               &transport_socket_pool_,
               &ssl_socket_pool_,
               NULL) {
-    SpdySession::SetPriorityDependencyDefaultForTesting(
-        GetParam().priority_to_dependency);
+    session_deps_.enable_priority_dependencies =
+        GetParam().priority_to_dependency;
+    session_ = CreateNetworkSession();
   }
 
-  virtual ~HttpProxyClientSocketPoolTest() {
-    SpdySession::SetPriorityDependencyDefaultForTesting(false);
-  }
+  virtual ~HttpProxyClientSocketPoolTest() {}
 
   void AddAuthToCache() {
     const base::string16 kFoo(base::ASCIIToUTF16("foo"));
@@ -219,7 +217,7 @@ class HttpProxyClientSocketPoolTest
   scoped_ptr<CertVerifier> cert_verifier_;
   SSLClientSocketPool ssl_socket_pool_;
 
-  const scoped_ptr<HttpNetworkSession> session_;
+  scoped_ptr<HttpNetworkSession> session_;
 
  protected:
   SpdyTestUtil spdy_util_;
diff --git a/net/net.gypi b/net/net.gypi
index b80e2bb..80e59a6 100644
--- a/net/net.gypi
+++ b/net/net.gypi
@@ -1138,6 +1138,8 @@
       'spdy/hpack/hpack_static_table.cc',
       'spdy/hpack/hpack_static_table.h',
       'spdy/http2_write_scheduler.h',
+      'spdy/http2_priority_dependencies.h',
+      'spdy/http2_priority_dependencies.cc',
       'spdy/priority_write_scheduler.h',
       'spdy/spdy_alt_svc_wire_format.cc',
       'spdy/spdy_alt_svc_wire_format.h',
@@ -1754,6 +1756,7 @@
       'spdy/hpack/hpack_round_trip_test.cc',
       'spdy/hpack/hpack_static_table_test.cc',
       'spdy/http2_write_scheduler_test.cc',
+      'spdy/http2_priority_dependencies_unittest.cc',
       'spdy/mock_spdy_framer_visitor.cc',
       'spdy/mock_spdy_framer_visitor.h',
       'spdy/priority_write_scheduler_test.cc',
diff --git a/net/spdy/http2_priority_dependencies.cc b/net/spdy/http2_priority_dependencies.cc
new file mode 100644
index 0000000..a09ef1d
--- /dev/null
+++ b/net/spdy/http2_priority_dependencies.cc
@@ -0,0 +1,51 @@
+// Copyright 2016 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.
+
+#include "net/spdy/http2_priority_dependencies.h"
+
+namespace net {
+
+Http2PriorityDependencies::Http2PriorityDependencies() {}
+
+Http2PriorityDependencies::~Http2PriorityDependencies() {}
+
+void Http2PriorityDependencies::OnStreamSynSent(
+    SpdyStreamId id,
+    SpdyPriority priority,
+    SpdyStreamId* dependent_stream_id,
+    bool* exclusive) {
+  DCHECK(entry_by_stream_id_.find(id) == entry_by_stream_id_.end());
+
+  *dependent_stream_id = 0ul;
+  *exclusive = true;
+
+  // Find the next highest entry in total order.
+  for (int i = priority; i >= kV3HighestPriority; --i) {
+    if (!id_priority_lists_[i].empty()) {
+      *dependent_stream_id = id_priority_lists_[i].back().first;
+      break;
+    }
+  }
+
+  id_priority_lists_[priority].push_back(std::make_pair(id, priority));
+  IdList::iterator it = id_priority_lists_[priority].end();
+  --it;
+  entry_by_stream_id_[id] = it;
+}
+
+void Http2PriorityDependencies::OnStreamDestruction(SpdyStreamId id) {
+  EntryMap::iterator emit = entry_by_stream_id_.find(id);
+
+  // This routine may be called without a matching call to
+  // OnStreamSynSent above, in the case of server push.  In that case,
+  // it's a no-op.
+  if (emit == entry_by_stream_id_.end())
+    return;
+
+  IdList::iterator it = emit->second;
+  id_priority_lists_[it->second].erase(it);
+  entry_by_stream_id_.erase(emit);
+}
+
+}  // namespace net
diff --git a/net/spdy/http2_priority_dependencies.h b/net/spdy/http2_priority_dependencies.h
new file mode 100644
index 0000000..8f4ced0
--- /dev/null
+++ b/net/spdy/http2_priority_dependencies.h
@@ -0,0 +1,60 @@
+// Copyright 2016 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.
+
+#ifndef NET_HTTP2_PRIORITY_DEPENDENCIES_H_
+#define NET_HTTP2_PRIORITY_DEPENDENCIES_H_
+
+#include <list>
+#include <map>
+
+#include "net/spdy/spdy_protocol.h"
+
+namespace net {
+
+// A helper class encapsulating the state and logic to set dependencies of
+// HTTP2 streams based on their SpdyPriority and the ordering
+// of creation and deletion of the streams.
+class NET_EXPORT_PRIVATE Http2PriorityDependencies {
+ public:
+  Http2PriorityDependencies();
+  ~Http2PriorityDependencies();
+
+  // Called when a stream SYN is sent to the server.  Note that in the
+  // case of server push, a stream may be created without this routine
+  // being called.  In such cases, the client ignores the stream's priority
+  // (as the server is effectively overriding the client's notions of
+  // priority anyway).
+  // On return, |*dependent_stream_id| is set to the stream id that
+  // this stream should be made dependent on, and |*exclusive| set to
+  // whether that dependency should be exclusive.
+  void OnStreamSynSent(SpdyStreamId id,
+                       SpdyPriority priority,
+                       SpdyStreamId* dependent_stream_id,
+                       bool* exclusive);
+
+  void OnStreamDestruction(SpdyStreamId id);
+
+ private:
+  // The requirements for the internal data structure for this class are:
+  //     a) Constant time insertion of entries at the end of the list,
+  //     b) Fast removal of any entry based on its id.
+  //     c) Constant time lookup of the entry at the end of the list.
+  // std::list would satisfy (a) & (c), but some form of map is
+  // needed for (b).  The priority must be included in the map
+  // entries so that deletion can determine which list in id_priority_lists_
+  // to erase from.
+  using IdList = std::list<std::pair<SpdyStreamId, SpdyPriority>>;
+  using EntryMap = std::map<SpdyStreamId, IdList::iterator>;
+
+  IdList id_priority_lists_[kV3LowestPriority + 1];
+
+  // Tracks the location of an id anywhere in the above vector of lists.
+  // Iterators to list elements remain valid until those particular elements
+  // are erased.
+  EntryMap entry_by_stream_id_;
+};
+
+}  // namespace net
+
+#endif  // NET_HTTP2_PRIORITY_DEPENDENCIES_H_
diff --git a/net/spdy/http2_priority_dependencies_unittest.cc b/net/spdy/http2_priority_dependencies_unittest.cc
new file mode 100644
index 0000000..05c482b
--- /dev/null
+++ b/net/spdy/http2_priority_dependencies_unittest.cc
@@ -0,0 +1,144 @@
+// Copyright 2016 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.
+
+#include "net/spdy/http2_priority_dependencies.h"
+
+#include "testing/platform_test.h"
+
+namespace net {
+
+class HttpPriorityDependencyTest : public PlatformTest {
+ public:
+  HttpPriorityDependencyTest() : next_id_(0u) {}
+
+  // Fixed priority values to use for testing.
+  enum { HIGHEST = 0, MEDIUM = 2, LOW = 4, LOWEST = 5 };
+
+  SpdyStreamId GetId() { return ++next_id_; }
+
+  void TestStreamCreation(SpdyStreamId new_id,
+                          SpdyPriority priority,
+                          SpdyStreamId expected_dependent_id) {
+    SpdyStreamId dependent_id = 999u;
+    bool exclusive = false;
+    dependency_state.OnStreamSynSent(new_id, priority, &dependent_id,
+                                     &exclusive);
+    EXPECT_EQ(expected_dependent_id, dependent_id);
+    EXPECT_TRUE(exclusive);
+  }
+
+  void OnStreamDestruction(SpdyStreamId id) {
+    dependency_state.OnStreamDestruction(id);
+  }
+
+ private:
+  SpdyStreamId next_id_;
+  Http2PriorityDependencies dependency_state;
+};
+
+// Confirm dependencies correct for entries at the same priority.
+TEST_F(HttpPriorityDependencyTest, SamePriority) {
+  Http2PriorityDependencies dependency_state;
+
+  const SpdyStreamId first_id = GetId();
+  const SpdyStreamId second_id = GetId();
+  const SpdyStreamId third_id = GetId();
+
+  TestStreamCreation(first_id, MEDIUM, 0u);
+  TestStreamCreation(second_id, MEDIUM, first_id);
+  TestStreamCreation(third_id, MEDIUM, second_id);
+}
+
+// Confirm dependencies correct for entries at different priorities, increasing.
+TEST_F(HttpPriorityDependencyTest, DifferentPriorityIncreasing) {
+  Http2PriorityDependencies dependency_state;
+
+  const SpdyStreamId first_id = GetId();
+  const SpdyStreamId second_id = GetId();
+  const SpdyStreamId third_id = GetId();
+
+  TestStreamCreation(first_id, LOWEST, 0u);
+  TestStreamCreation(second_id, MEDIUM, 0u);
+  TestStreamCreation(third_id, HIGHEST, 0u);
+}
+
+// Confirm dependencies correct for entries at different priorities, increasing.
+TEST_F(HttpPriorityDependencyTest, DifferentPriorityDecreasing) {
+  Http2PriorityDependencies dependency_state;
+
+  const SpdyStreamId first_id = GetId();
+  const SpdyStreamId second_id = GetId();
+  const SpdyStreamId third_id = GetId();
+
+  TestStreamCreation(first_id, HIGHEST, 0u);
+  TestStreamCreation(second_id, MEDIUM, first_id);
+  TestStreamCreation(third_id, LOWEST, second_id);
+}
+
+// Confirm dependencies correct if requests are completed between before
+// next creation.
+TEST_F(HttpPriorityDependencyTest, CompletionBeforeIssue) {
+  Http2PriorityDependencies dependency_state;
+
+  const SpdyStreamId first_id = GetId();
+  const SpdyStreamId second_id = GetId();
+  const SpdyStreamId third_id = GetId();
+
+  TestStreamCreation(first_id, HIGHEST, 0u);
+  OnStreamDestruction(first_id);
+  TestStreamCreation(second_id, MEDIUM, 0u);
+  OnStreamDestruction(second_id);
+  TestStreamCreation(third_id, LOWEST, 0u);
+}
+
+// Confirm dependencies correct if some requests are completed between before
+// next creation.
+TEST_F(HttpPriorityDependencyTest, SomeCompletions) {
+  Http2PriorityDependencies dependency_state;
+
+  const SpdyStreamId first_id = GetId();
+  const SpdyStreamId second_id = GetId();
+  const SpdyStreamId third_id = GetId();
+
+  TestStreamCreation(first_id, HIGHEST, 0u);
+  TestStreamCreation(second_id, MEDIUM, first_id);
+  OnStreamDestruction(second_id);
+  TestStreamCreation(third_id, LOWEST, first_id);
+}
+
+// A more complex example parallel to a simple web page.
+TEST_F(HttpPriorityDependencyTest, Complex) {
+  Http2PriorityDependencies dependency_state;
+
+  const SpdyStreamId first_id = GetId();
+  const SpdyStreamId second_id = GetId();
+  const SpdyStreamId third_id = GetId();
+  const SpdyStreamId fourth_id = GetId();
+  const SpdyStreamId fifth_id = GetId();
+  const SpdyStreamId sixth_id = GetId();
+  const SpdyStreamId seventh_id = GetId();
+  const SpdyStreamId eighth_id = GetId();
+  const SpdyStreamId nineth_id = GetId();
+  const SpdyStreamId tenth_id = GetId();
+
+  TestStreamCreation(first_id, HIGHEST, 0u);
+  TestStreamCreation(second_id, MEDIUM, first_id);
+  TestStreamCreation(third_id, MEDIUM, second_id);
+  OnStreamDestruction(first_id);
+  TestStreamCreation(fourth_id, MEDIUM, third_id);
+  TestStreamCreation(fifth_id, LOWEST, fourth_id);
+  TestStreamCreation(sixth_id, MEDIUM, fourth_id);
+  OnStreamDestruction(third_id);
+  TestStreamCreation(seventh_id, MEDIUM, sixth_id);
+  TestStreamCreation(eighth_id, LOW, seventh_id);
+  OnStreamDestruction(second_id);
+  OnStreamDestruction(fourth_id);
+  OnStreamDestruction(fifth_id);
+  OnStreamDestruction(sixth_id);
+  OnStreamDestruction(seventh_id);
+  TestStreamCreation(nineth_id, MEDIUM, 0u);
+  TestStreamCreation(tenth_id, HIGHEST, 0u);
+}
+
+}  // namespace net
diff --git a/net/spdy/spdy_http_stream_unittest.cc b/net/spdy/spdy_http_stream_unittest.cc
index 69ef370..9bd5a70 100644
--- a/net/spdy/spdy_http_stream_unittest.cc
+++ b/net/spdy/spdy_http_stream_unittest.cc
@@ -82,14 +82,11 @@ class SpdyHttpStreamTest : public testing::Test,
   SpdyHttpStreamTest()
       : spdy_util_(GetProtocol(), GetDependenciesFromPriority()),
         session_deps_(GetProtocol()) {
-    SpdySession::SetPriorityDependencyDefaultForTesting(
-        GetDependenciesFromPriority());
+    session_deps_.enable_priority_dependencies = GetDependenciesFromPriority();
     session_deps_.net_log = &net_log_;
   }
 
-  ~SpdyHttpStreamTest() {
-    SpdySession::SetPriorityDependencyDefaultForTesting(false);
-  }
+  ~SpdyHttpStreamTest() {}
 
  protected:
   NextProto GetProtocol() const {
diff --git a/net/spdy/spdy_network_transaction_unittest.cc b/net/spdy/spdy_network_transaction_unittest.cc
index 88b34eb..cecfe7c 100644
--- a/net/spdy/spdy_network_transaction_unittest.cc
+++ b/net/spdy/spdy_network_transaction_unittest.cc
@@ -114,6 +114,8 @@ void UpdateSpdySessionDependencies(SpdyNetworkTransactionTestParams test_params,
                            "www.example.org", 443),
         expiration);
   }
+  session_deps->enable_priority_dependencies =
+      test_params.priority_to_dependency;
 }
 
 scoped_ptr<SpdySessionDependencies> CreateSpdySessionDependencies(
@@ -140,8 +142,6 @@ class SpdyNetworkTransactionTest
  protected:
   SpdyNetworkTransactionTest()
       : spdy_util_(GetParam().protocol, GetParam().priority_to_dependency) {
-    SpdySession::SetPriorityDependencyDefaultForTesting(
-        GetParam().priority_to_dependency);
     spdy_util_.set_default_url(GURL(GetDefaultUrl()));
   }
 
@@ -150,7 +150,6 @@ class SpdyNetworkTransactionTest
     // destruction.
     upload_data_stream_.reset();
     base::RunLoop().RunUntilIdle();
-    SpdySession::SetPriorityDependencyDefaultForTesting(false);
   }
 
   void SetUp() override {
diff --git a/net/spdy/spdy_proxy_client_socket_unittest.cc b/net/spdy/spdy_proxy_client_socket_unittest.cc
index 20ba5a5..cda99f0 100644
--- a/net/spdy/spdy_proxy_client_socket_unittest.cc
+++ b/net/spdy/spdy_proxy_client_socket_unittest.cc
@@ -179,14 +179,12 @@ SpdyProxyClientSocketTest::SpdyProxyClientSocketTest()
                                  proxy_,
                                  PRIVACY_MODE_DISABLED) {
   session_deps_.net_log = net_log_.bound().net_log();
-  SpdySession::SetPriorityDependencyDefaultForTesting(
-      GetDependenciesFromPriority());
+  session_deps_.enable_priority_dependencies = GetDependenciesFromPriority();
 }
 
 SpdyProxyClientSocketTest::~SpdyProxyClientSocketTest() {
   EXPECT_TRUE(data_->AllWriteDataConsumed());
   EXPECT_TRUE(data_->AllReadDataConsumed());
-  SpdySession::SetPriorityDependencyDefaultForTesting(false);
 }
 
 void SpdyProxyClientSocketTest::TearDown() {
diff --git a/net/spdy/spdy_session.cc b/net/spdy/spdy_session.cc
index da9589a..3ab0112 100644
--- a/net/spdy/spdy_session.cc
+++ b/net/spdy/spdy_session.cc
@@ -13,7 +13,6 @@
 #include "base/compiler_specific.h"
 #include "base/location.h"
 #include "base/logging.h"
-#include "base/metrics/field_trial.h"
 #include "base/metrics/histogram_macros.h"
 #include "base/metrics/sparse_histogram.h"
 #include "base/profiler/scoped_tracker.h"
@@ -61,14 +60,6 @@ const int kHungIntervalSeconds = 10;
 // Minimum seconds that unclaimed pushed streams will be kept in memory.
 const int kMinPushedStreamLifetimeSeconds = 300;
 
-// Field trial constants
-const char kSpdyDependenciesFieldTrial[] = "SpdyEnableDependencies";
-const char kSpdyDepencenciesFieldTrialEnable[] = "Enable";
-
-// Whether the creation of SPDY dependencies based on priority is
-// enabled by default.
-static bool priority_dependency_enabled_default = false;
-
 scoped_ptr<base::ListValue> SpdyHeaderBlockToListValue(
     const SpdyHeaderBlock& headers,
     NetLogCaptureMode capture_mode) {
@@ -689,6 +680,7 @@ SpdySession::SpdySession(
     bool verify_domain_authentication,
     bool enable_sending_initial_data,
     bool enable_ping_based_connection_checking,
+    bool enable_priority_dependencies,
     NextProto default_protocol,
     size_t session_max_recv_window_size,
     size_t stream_max_recv_window_size,
@@ -748,7 +740,7 @@ SpdySession::SpdySession(
       hung_interval_(base::TimeDelta::FromSeconds(kHungIntervalSeconds)),
       proxy_delegate_(proxy_delegate),
       time_func_(time_func),
-      send_priority_dependency_(priority_dependency_enabled_default),
+      priority_dependencies_enabled_(enable_priority_dependencies),
       weak_factory_(this) {
   DCHECK_GE(protocol_, kProtoSPDYMinimumVersion);
   DCHECK_LE(protocol_, kProtoSPDYMaximumVersion);
@@ -758,10 +750,6 @@ SpdySession::SpdySession(
       base::Bind(&NetLogSpdySessionCallback, &host_port_proxy_pair()));
   next_unclaimed_push_stream_sweep_time_ = time_func_() +
       base::TimeDelta::FromSeconds(kMinPushedStreamLifetimeSeconds);
-  if (base::FieldTrialList::FindFullName(kSpdyDependenciesFieldTrial) ==
-      kSpdyDepencenciesFieldTrialEnable) {
-    send_priority_dependency_ = true;
-  }
   // TODO(mbelshe): consider randomization of the stream_hi_water_mark.
 }
 
@@ -1091,11 +1079,6 @@ bool SpdySession::CloseOneIdleConnection() {
   return false;
 }
 
-// static
-void SpdySession::SetPriorityDependencyDefaultForTesting(bool enable) {
-  priority_dependency_enabled_default = enable;
-}
-
 void SpdySession::EnqueueStreamWrite(
     const base::WeakPtr<SpdyStream>& stream,
     SpdyFrameType frame_type,
@@ -1144,38 +1127,13 @@ scoped_ptr<SpdyFrame> SpdySession::CreateSynStream(
     headers.set_priority(spdy_priority);
     headers.set_has_priority(true);
 
-    if (send_priority_dependency_) {
-      // Set dependencies to reflect request priority.  A newly created
-      // stream should be dependent on the most recent previously created
-      // stream of the same priority level.  The newly created stream
-      // should also have all streams of a lower priority level dependent
-      // on it, which is guaranteed by setting the exclusive bit.
-      //
-      // Note that this depends on stream ids being allocated in a monotonically
-      // increasing fashion, and on all streams in
-      // active_streams_{,by_priority_} having stream ids set.
-      for (int i = priority; i >= IDLE; --i) {
-        if (active_streams_by_priority_[i].empty())
-          continue;
-
-        auto candidate_it = active_streams_by_priority_[i].rbegin();
-
-        // |active_streams_by_priority_| is updated before the
-        // SYN stream frame is created, so the current streams
-        // id is already on the list.  Skip over it, skipping this
-        // priority level if it's singular.
-        if (candidate_it->second->stream_id() == stream_id)
-          ++candidate_it;
-        if (candidate_it == active_streams_by_priority_[i].rend())
-          continue;
-
-        headers.set_parent_stream_id(candidate_it->second->stream_id());
-        break;
-      }
-
-      // If there are no streams of priority <= the current stream, the
-      // current stream will default to a child of the idle node (0).
-      headers.set_exclusive(true);
+    if (priority_dependencies_enabled_) {
+      SpdyStreamId dependent_stream_id = 0;
+      bool exclusive = false;
+      priority_dependency_state_.OnStreamSynSent(
+          stream_id, spdy_priority, &dependent_stream_id, &exclusive);
+      headers.set_parent_stream_id(dependent_stream_id);
+      headers.set_exclusive(exclusive);
     }
 
     headers.set_fin((flags & CONTROL_FLAG_FIN) != 0);
@@ -1362,8 +1320,8 @@ void SpdySession::CloseActiveStreamIterator(ActiveStreamMap::iterator it,
 
   scoped_ptr<SpdyStream> owned_stream(it->second.stream);
   active_streams_.erase(it);
-  active_streams_by_priority_[owned_stream->priority()].erase(
-      owned_stream->stream_id());
+  if (priority_dependencies_enabled_)
+    priority_dependency_state_.OnStreamDestruction(owned_stream->stream_id());
 
   // TODO(akalin): When SpdyStream was ref-counted (and
   // |unclaimed_pushed_streams_| held scoped_refptr<SpdyStream>), this
@@ -2035,8 +1993,6 @@ void SpdySession::InsertActivatedStream(scoped_ptr<SpdyStream> stream) {
   std::pair<ActiveStreamMap::iterator, bool> result =
       active_streams_.insert(
           std::make_pair(stream_id, ActiveStreamInfo(stream.get())));
-  active_streams_by_priority_[stream->priority()].insert(
-      std::make_pair(stream_id, stream.get()));
   CHECK(result.second);
   ignore_result(stream.release());
 }
diff --git a/net/spdy/spdy_session.h b/net/spdy/spdy_session.h
index 343aa2d..5ce8fec 100644
--- a/net/spdy/spdy_session.h
+++ b/net/spdy/spdy_session.h
@@ -32,6 +32,7 @@
 #include "net/socket/ssl_client_socket.h"
 #include "net/socket/stream_socket.h"
 #include "net/spdy/buffered_spdy_framer.h"
+#include "net/spdy/http2_priority_dependencies.h"
 #include "net/spdy/spdy_buffer.h"
 #include "net/spdy/spdy_framer.h"
 #include "net/spdy/spdy_header_block.h"
@@ -290,6 +291,7 @@ class NET_EXPORT SpdySession : public BufferedSpdyFramerVisitorInterface,
               bool verify_domain_authentication,
               bool enable_sending_initial_data,
               bool enable_ping_based_connection_checking,
+              bool enable_priority_dependencies,
               NextProto default_protocol,
               size_t session_max_recv_window_size,
               size_t stream_max_recv_window_size,
@@ -1001,10 +1003,6 @@ class NET_EXPORT SpdySession : public BufferedSpdyFramerVisitorInterface,
 
   bool check_ping_status_pending() const { return check_ping_status_pending_; }
 
-  // Set whether priority->dependency conversion is enabled
-  // by default for all future SpdySessions.
-  static void SetPriorityDependencyDefaultForTesting(bool enable);
-
   // Whether Do{Read,Write}Loop() is in the call stack. Useful for
   // making sure we don't destroy ourselves prematurely in that case.
   bool in_io_loop_;
@@ -1050,14 +1048,6 @@ class NET_EXPORT SpdySession : public BufferedSpdyFramerVisitorInterface,
   // them?
   ActiveStreamMap active_streams_;
 
-  // Per-priority map from stream id to all active streams.  This map will
-  // contain the same set of streams as |active_streams_|.  It is used for
-  // setting dependencies to match incoming requests RequestPriority.
-  //
-  // |active_streams_by_priority_| does *not* own its SpdyStream objects.
-  std::map<SpdyStreamId, SpdyStream*>
-      active_streams_by_priority_[NUM_PRIORITIES];
-
   UnclaimedPushedStreamContainer unclaimed_pushed_streams_;
 
   // Set of all created streams but that have not yet sent any frames.
@@ -1230,9 +1220,8 @@ class NET_EXPORT SpdySession : public BufferedSpdyFramerVisitorInterface,
 
   TimeFunc time_func_;
 
-  // Should priority-based dependency information be sent in stream header
-  // frames.
-  bool send_priority_dependency_;
+  const bool priority_dependencies_enabled_;
+  Http2PriorityDependencies priority_dependency_state_;
 
   // Used for posting asynchronous IO tasks.  We use this even though
   // SpdySession is refcounted because we don't need to keep the SpdySession
diff --git a/net/spdy/spdy_session_pool.cc b/net/spdy/spdy_session_pool.cc
index afc285c..b84c8bb 100644
--- a/net/spdy/spdy_session_pool.cc
+++ b/net/spdy/spdy_session_pool.cc
@@ -36,6 +36,7 @@ SpdySessionPool::SpdySessionPool(
     const base::WeakPtr<HttpServerProperties>& http_server_properties,
     TransportSecurityState* transport_security_state,
     bool enable_ping_based_connection_checking,
+    bool enable_priority_dependencies,
     NextProto default_protocol,
     size_t session_max_recv_window_size,
     size_t stream_max_recv_window_size,
@@ -49,6 +50,7 @@ SpdySessionPool::SpdySessionPool(
       enable_sending_initial_data_(true),
       enable_ping_based_connection_checking_(
           enable_ping_based_connection_checking),
+      enable_priority_dependencies_(enable_priority_dependencies),
       // TODO(akalin): Force callers to have a valid value of
       // |default_protocol_|.
       default_protocol_((default_protocol == kProtoUnknown) ? kProtoSPDY31
@@ -95,9 +97,10 @@ base::WeakPtr<SpdySession> SpdySessionPool::CreateAvailableSessionFromSocket(
   scoped_ptr<SpdySession> new_session(new SpdySession(
       key, http_server_properties_, transport_security_state_,
       verify_domain_authentication_, enable_sending_initial_data_,
-      enable_ping_based_connection_checking_, default_protocol_,
-      session_max_recv_window_size_, stream_max_recv_window_size_, time_func_,
-      proxy_delegate_, net_log.net_log()));
+      enable_ping_based_connection_checking_, enable_priority_dependencies_,
+      default_protocol_, session_max_recv_window_size_,
+      stream_max_recv_window_size_, time_func_, proxy_delegate_,
+      net_log.net_log()));
 
   new_session->InitializeWithSocket(std::move(connection), this, is_secure,
                                     certificate_error_code);
diff --git a/net/spdy/spdy_session_pool.h b/net/spdy/spdy_session_pool.h
index d02ecb2..eeae314 100644
--- a/net/spdy/spdy_session_pool.h
+++ b/net/spdy/spdy_session_pool.h
@@ -55,6 +55,7 @@ class NET_EXPORT SpdySessionPool
       const base::WeakPtr<HttpServerProperties>& http_server_properties,
       TransportSecurityState* transport_security_state,
       bool enable_ping_based_connection_checking,
+      bool enable_priority_dependencies,
       NextProto default_protocol,
       size_t session_max_recv_window_size,
       size_t stream_max_recv_window_size,
@@ -227,6 +228,7 @@ class NET_EXPORT SpdySessionPool
   bool verify_domain_authentication_;
   bool enable_sending_initial_data_;
   bool enable_ping_based_connection_checking_;
+  const bool enable_priority_dependencies_;
   const NextProto default_protocol_;
   size_t session_max_recv_window_size_;
   size_t stream_max_recv_window_size_;
diff --git a/net/spdy/spdy_session_pool_unittest.cc b/net/spdy/spdy_session_pool_unittest.cc
index cb849d3..cbd41c2 100644
--- a/net/spdy/spdy_session_pool_unittest.cc
+++ b/net/spdy/spdy_session_pool_unittest.cc
@@ -520,8 +520,8 @@ TEST_P(SpdySessionPoolTest, IPAddressChanged) {
   // can ignore issues of how dependencies are set.  We default to
   // setting them (when doing the appropriate protocol) since that's
   // where we're eventually headed for all HTTP/2 connections.
-  SpdyTestUtil spdy_util(GetParam(), true);
-  SpdySession::SetPriorityDependencyDefaultForTesting(true);
+  session_deps_.enable_priority_dependencies = true;
+  SpdyTestUtil spdy_util(GetParam(), /*enable_priority_dependencies*/ true);
 
   MockRead reads[] = {
       MockRead(SYNCHRONOUS, ERR_IO_PENDING)  // Stall forever.
@@ -630,7 +630,6 @@ TEST_P(SpdySessionPoolTest, IPAddressChanged) {
   EXPECT_TRUE(delegateB.StreamIsClosed());
   EXPECT_EQ(ERR_NETWORK_CHANGED, delegateB.WaitForClose());
 #endif  // defined(OS_ANDROID) || defined(OS_WIN) || defined(OS_IOS)
-  SpdySession::SetPriorityDependencyDefaultForTesting(false);
 }
 
 TEST_P(SpdySessionPoolTest, FindAvailableSession) {
diff --git a/net/spdy/spdy_session_unittest.cc b/net/spdy/spdy_session_unittest.cc
index 6e5797f..91547b4 100644
--- a/net/spdy/spdy_session_unittest.cc
+++ b/net/spdy/spdy_session_unittest.cc
@@ -139,8 +139,7 @@ class SpdySessionTest : public PlatformTest,
         key_(test_host_port_pair_,
              ProxyServer::Direct(),
              PRIVACY_MODE_DISABLED) {
-    SpdySession::SetPriorityDependencyDefaultForTesting(
-        GetDependenciesFromPriority());
+    session_deps_.enable_priority_dependencies = GetDependenciesFromPriority();
   }
 
   virtual ~SpdySessionTest() {
@@ -150,7 +149,6 @@ class SpdySessionTest : public PlatformTest,
         HttpNetworkSession::NORMAL_SOCKET_POOL, old_max_pool_sockets_);
     ClientSocketPoolManager::set_max_sockets_per_group(
         HttpNetworkSession::NORMAL_SOCKET_POOL, old_max_group_sockets_);
-    SpdySession::SetPriorityDependencyDefaultForTesting(false);
   }
 
   void SetUp() override {
diff --git a/net/spdy/spdy_stream_unittest.cc b/net/spdy/spdy_stream_unittest.cc
index eea3352..70bbc49 100644
--- a/net/spdy/spdy_stream_unittest.cc
+++ b/net/spdy/spdy_stream_unittest.cc
@@ -69,14 +69,12 @@ class SpdyStreamTest : public ::testing::Test,
   SpdyStreamTest()
       : spdy_util_(GetProtocol(), GetDependenciesFromPriority()),
         session_deps_(GetProtocol()),
-        session_(SpdySessionDependencies::SpdyCreateSession(&session_deps_)),
         offset_(0) {
-    SpdySession::SetPriorityDependencyDefaultForTesting(
-        GetDependenciesFromPriority());
+    session_deps_.enable_priority_dependencies = GetDependenciesFromPriority();
+    session_ = SpdySessionDependencies::SpdyCreateSession(&session_deps_);
   }
 
   ~SpdyStreamTest() {
-    SpdySession::SetPriorityDependencyDefaultForTesting(false);
   }
 
   base::WeakPtr<SpdySession> CreateDefaultSpdySession() {
diff --git a/net/spdy/spdy_test_util_common.cc b/net/spdy/spdy_test_util_common.cc
index 627eeee..2a37dab 100644
--- a/net/spdy/spdy_test_util_common.cc
+++ b/net/spdy/spdy_test_util_common.cc
@@ -341,6 +341,7 @@ SpdySessionDependencies::SpdySessionDependencies(NextProto protocol)
       enable_ping(false),
       enable_user_alternate_protocol_ports(false),
       enable_npn(true),
+      enable_priority_dependencies(true),
       protocol(protocol),
       session_max_recv_window_size(
           SpdySession::GetDefaultInitialWindowSize(protocol)),
@@ -377,6 +378,7 @@ SpdySessionDependencies::SpdySessionDependencies(
       enable_ping(false),
       enable_user_alternate_protocol_ports(false),
       enable_npn(true),
+      enable_priority_dependencies(true),
       protocol(protocol),
       session_max_recv_window_size(
           SpdySession::GetDefaultInitialWindowSize(protocol)),
@@ -424,6 +426,8 @@ HttpNetworkSession::Params SpdySessionDependencies::CreateSessionParams(
   params.enable_user_alternate_protocol_ports =
       session_deps->enable_user_alternate_protocol_ports;
   params.enable_npn = session_deps->enable_npn;
+  params.enable_priority_dependencies =
+      session_deps->enable_priority_dependencies;
   params.spdy_default_protocol = session_deps->protocol;
   params.spdy_session_max_recv_window_size =
       session_deps->session_max_recv_window_size;
@@ -1042,8 +1046,13 @@ SpdyFrame* SpdyTestUtil::ConstructSpdySyn(int stream_id,
   // Get the stream id of the next highest priority request
   // (most recent request of the same priority, or last request of
   // an earlier priority).
+  // Note that this is a duplicate of the logic in Http2PriorityDependencies
+  // (slightly transformed as this is based on RequestPriority and that logic
+  // on SpdyPriority, but only slightly transformed) and hence tests using
+  // this function do not effectively test that logic.
+  // That logic is tested by the Http2PriorityDependencies unit tests.
   int parent_stream_id = 0;
-  for (int q = priority; q >= IDLE; --q) {
+  for (int q = priority; q <= HIGHEST; ++q) {
     if (!priority_to_stream_id_list_[q].empty()) {
       parent_stream_id = priority_to_stream_id_list_[q].back();
       break;
diff --git a/net/spdy/spdy_test_util_common.h b/net/spdy/spdy_test_util_common.h
index e4ad8ec..64992a6 100644
--- a/net/spdy/spdy_test_util_common.h
+++ b/net/spdy/spdy_test_util_common.h
@@ -197,6 +197,7 @@ struct SpdySessionDependencies {
   bool enable_ping;
   bool enable_user_alternate_protocol_ports;
   bool enable_npn;
+  bool enable_priority_dependencies;
   NextProto protocol;
   size_t session_max_recv_window_size;
   size_t stream_max_recv_window_size;
diff --git a/testing/variations/fieldtrial_testing_config_android.json b/testing/variations/fieldtrial_testing_config_android.json
index dc85f56..e2b80af 100644
--- a/testing/variations/fieldtrial_testing_config_android.json
+++ b/testing/variations/fieldtrial_testing_config_android.json
@@ -333,11 +333,6 @@
             "group_name": "Enabled"
         }
     ],
-    "SpdyEnableDependencies": [
-        {
-            "group_name": "Enable"
-        }
-    ],
     "SpeculativeResourcePrefetching": [
         {
             "group_name": "v=1a:Prefetching=Enabled:Predictor=Url"
diff --git a/testing/variations/fieldtrial_testing_config_chromeos.json b/testing/variations/fieldtrial_testing_config_chromeos.json
index 2312ee9..9a03f0b 100644
--- a/testing/variations/fieldtrial_testing_config_chromeos.json
+++ b/testing/variations/fieldtrial_testing_config_chromeos.json
@@ -145,11 +145,6 @@
             "group_name": "ExperimentYes"
         }
     ],
-    "SpdyEnableDependencies": [
-        {
-            "group_name": "Enable"
-        }
-    ],
     "StrictSecureCookies": [
         {
             "group_name": "Enabled"
diff --git a/testing/variations/fieldtrial_testing_config_ios.json b/testing/variations/fieldtrial_testing_config_ios.json
index 67899aa..a2e409b 100644
--- a/testing/variations/fieldtrial_testing_config_ios.json
+++ b/testing/variations/fieldtrial_testing_config_ios.json
@@ -56,11 +56,6 @@
             "group_name": "Enabled"
         }
     ],
-    "SpdyEnableDependencies": [
-        {
-            "group_name": "Enable"
-        }
-    ],
     "SyncHttpContentCompression": [
         {
             "group_name": "Enabled"
diff --git a/testing/variations/fieldtrial_testing_config_linux.json b/testing/variations/fieldtrial_testing_config_linux.json
index ec15528..cee9d02 100644
--- a/testing/variations/fieldtrial_testing_config_linux.json
+++ b/testing/variations/fieldtrial_testing_config_linux.json
@@ -192,11 +192,6 @@
             "group_name": "ExperimentYes"
         }
     ],
-    "SpdyEnableDependencies": [
-        {
-            "group_name": "Enable"
-        }
-    ],
     "StrictSecureCookies": [
         {
             "group_name": "Enabled"
diff --git a/testing/variations/fieldtrial_testing_config_mac.json b/testing/variations/fieldtrial_testing_config_mac.json
index 5ad2471..b3cbf6f 100644
--- a/testing/variations/fieldtrial_testing_config_mac.json
+++ b/testing/variations/fieldtrial_testing_config_mac.json
@@ -208,11 +208,6 @@
             "group_name": "ExperimentYes"
         }
     ],
-    "SpdyEnableDependencies": [
-        {
-            "group_name": "Enable"
-        }
-    ],
     "StrictSecureCookies": [
         {
             "group_name": "Enabled"
diff --git a/testing/variations/fieldtrial_testing_config_win.json b/testing/variations/fieldtrial_testing_config_win.json
index 79e43ec..45b55af 100644
--- a/testing/variations/fieldtrial_testing_config_win.json
+++ b/testing/variations/fieldtrial_testing_config_win.json
@@ -285,11 +285,6 @@
             "group_name": "ExperimentYes"
         }
     ],
-    "SpdyEnableDependencies": [
-        {
-            "group_name": "Enable"
-        }
-    ],
     "StrictSecureCookies": [
         {
             "group_name": "Enabled"