Added a field trial (finch experiment) to disable SPDY for x% of users.

chrome/browser/io_thread.cc

 // 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.
 
 #include "chrome/browser/io_thread.h"
 
 #include <vector>
 
 #include "base/bind.h"
 #include "base/bind_helpers.h"
@@ skipping 85 matching lines @@
 
 // The IOThread object must outlive any tasks posted to the IO thread before the
 // Quit task, so base::Bind() calls are not refcounted.
 
 namespace {
 
 const char kQuicFieldTrialName[] = "QUIC";
 const char kQuicFieldTrialEnabledGroupName[] = "Enabled";
 const char kQuicFieldTrialHttpsEnabledGroupName[] = "HttpsEnabled";
 
+const char kSpdyFieldTrialName[] = "SPDY";
+const char kSpdyFieldTrialDisabledGroupName[] = "SpdyDisabled";
+
 #if defined(OS_MACOSX) && !defined(OS_IOS)
 void ObserveKeychainEvents() {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
   net::CertDatabase::GetInstance()->SetMessageLoopForKeychainEvents();
 }
 #endif
 
 // Used for the "system" URLRequestContext.
 class SystemURLRequestContext : public net::URLRequestContext {
  public:
@@ skipping 562 matching lines @@
 
 void IOThread::InitializeNetworkOptions(const CommandLine& command_line) {
   if (command_line.HasSwitch(switches::kEnableFileCookies)) {
     // Enable cookie storage for file:// URLs.  Must do this before the first
     // Profile (and therefore the first CookieMonster) is created.
     net::CookieMonster::EnableFileScheme();
   }
 
   // Only handle use-spdy command line flags if "spdy.disabled" preference is
   // not disabled via policy.
-  if (!is_spdy_disabled_by_policy_) {
+  if (is_spdy_disabled_by_policy_) {
+    base::FieldTrial* trial = base::FieldTrialList::Find(kSpdyFieldTrialName);
+    if (trial)
+      trial->Disable();
+  } else {
+    std::string spdy_trial_group =
+        base::FieldTrialList::FindFullName(kSpdyFieldTrialName);
+
     if (command_line.HasSwitch(switches::kEnableIPPooling))
       globals_->enable_spdy_ip_pooling.set(true);
 
     if (command_line.HasSwitch(switches::kDisableIPPooling))
       globals_->enable_spdy_ip_pooling.set(false);
 
     if (command_line.HasSwitch(switches::kEnableSpdyCredentialFrames))
       globals_->enable_spdy_credential_frames.set(true);
 
     if (command_line.HasSwitch(switches::kEnableWebSocketOverSpdy)) {
       // Enable WebSocket over SPDY.
       net::WebSocketJob::set_websocket_over_spdy_enabled(true);
     }
+
     if (command_line.HasSwitch(switches::kMaxSpdyConcurrentStreams)) {
       globals_->max_spdy_concurrent_streams_limit.set(
           GetSwitchValueAsInt(command_line,
                               switches::kMaxSpdyConcurrentStreams));
     }
     if (command_line.HasSwitch(switches::kTrustedSpdyProxy)) {
       globals_->trusted_spdy_proxy.set(
           command_line.GetSwitchValueASCII(switches::kTrustedSpdyProxy));
     }
     if (command_line.HasSwitch(switches::kIgnoreUrlFetcherCertRequests))
       net::URLFetcher::SetIgnoreCertificateRequests(true);
 
     if (command_line.HasSwitch(switches::kUseSpdy)) {
       std::string spdy_mode =
           command_line.GetSwitchValueASCII(switches::kUseSpdy);
       EnableSpdy(spdy_mode);
     } else if (command_line.HasSwitch(switches::kEnableHttp2Draft04)) {
       net::HttpStreamFactory::EnableNpnHttp2Draft04();
     } else if (command_line.HasSwitch(switches::kEnableSpdy4a2)) {
       net::HttpStreamFactory::EnableNpnSpdy4a2();
     } else if (command_line.HasSwitch(switches::kDisableSpdy31)) {
       net::HttpStreamFactory::EnableNpnSpdy3();
     } else if (command_line.HasSwitch(switches::kEnableNpn)) {
       net::HttpStreamFactory::EnableNpnSpdy();
     } else if (command_line.HasSwitch(switches::kEnableNpnHttpOnly)) {
       net::HttpStreamFactory::EnableNpnHttpOnly();
     } else {
-      // Use SPDY/3.1 by default.
-      net::HttpStreamFactory::EnableNpnSpdy31();
+      if (spdy_trial_group == kSpdyFieldTrialDisabledGroupName &&
+          !command_line.HasSwitch(switches::kEnableWebSocketOverSpdy)) {
+         net::HttpStreamFactory::set_spdy_enabled(false);
+      } else {
+        // Use SPDY/3.1 by default.
+        net::HttpStreamFactory::EnableNpnSpdy31();
+      }
     }
   }
 
   // TODO(rch): Make the client socket factory a per-network session
   // instance, constructed from a NetworkSession::Params, to allow us
   // to move this option to IOThread::Globals &
   // HttpNetworkSession::Params.
   if (command_line.HasSwitch(switches::kEnableTcpFastOpen))
     net::SetTCPFastOpenEnabled(true);
 }
@@ skipping 274 matching lines @@
   if (command_line.HasSwitch(switches::kDisableQuicHttps))
     return false;
 
   if (command_line.HasSwitch(switches::kEnableQuicHttps))
     return true;
 
   // HTTPS over QUIC should only be enabled if we are in the https
   // field trial group.
   return quic_trial_group == kQuicFieldTrialHttpsEnabledGroupName;
 }