This change enables FieldTrial for SPDY. When --use-spdy=npn is used, field test won't be enabled.

However, when that flag is missing, A/B test is added to browser_main.cc. Trial A: use npn and spdy. B: use npn but no spdy. C: do nothing. A and B are set to zero for now
The histograms we collect are: 
1. Page begin to finish time when spdy is enabled/disabled across all sites;
2. Page begin to finish time when spdy is used on sites that support spdy and when spdy is intentionally ignored. 


BUG=43997
TEST=Don't use --use-spdy=npn, manually change _npn_nospdy and _npn_withspdy percentile and go to spdy supported sites.

Review URL: http://codereview.chromium.org/2036012

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@47896 0039d316-1c4b-4281-b951-d872f2087c98

7 files changed, 90 insertions, 16 deletions

diff --git a/chrome/browser/browser_init.cc b/chrome/browser/browser_init.cc
index e20dfa2..7e5b2fd 100644
--- a/chrome/browser/browser_init.cc
+++ b/chrome/browser/browser_init.cc
@@ -50,7 +50,6 @@
 #include "grit/locale_settings.h"
 #include "grit/theme_resources.h"
 #include "net/base/net_util.h"
-#include "net/http/http_network_layer.h"
 #include "net/url_request/url_request.h"
 #include "webkit/glue/webkit_glue.h"
 
@@ -1008,12 +1007,6 @@ bool BrowserInit::ProcessCmdLineImpl(const CommandLine& command_line,
     }
   }
 
-  if (command_line.HasSwitch(switches::kUseSpdy)) {
-    std::string spdy_mode =
-        command_line.GetSwitchValueASCII(switches::kUseSpdy);
-    net::HttpNetworkLayer::EnableSpdy(spdy_mode);
-  }
-
   if (command_line.HasSwitch(switches::kExplicitlyAllowedPorts)) {
     std::wstring allowed_ports =
       command_line.GetSwitchValue(switches::kExplicitlyAllowedPorts);
diff --git a/chrome/browser/browser_main.cc b/chrome/browser/browser_main.cc
index 1ccb00f..4f69109 100644
--- a/chrome/browser/browser_main.cc
+++ b/chrome/browser/browser_main.cc
@@ -73,6 +73,7 @@
 #include "grit/generated_resources.h"
 #include "net/base/cookie_monster.h"
 #include "net/base/net_module.h"
+#include "net/http/http_network_layer.h"
 #include "net/http/http_network_session.h"
 #include "net/http/http_network_transaction.h"
 #include "net/socket/client_socket_pool_base.h"
@@ -707,9 +708,52 @@ int BrowserMain(const MainFunctionParams& parameters) {
   net::EnsureWinsockInit();
 #endif  // defined(OS_WIN)
 
+  // Initialize statistical testing infrastructure for entire browser.
+  FieldTrialList field_trial;
+
+  // When --use-spdy not set, users will be in A/B test for spdy.
+  // group A (_npn_with_spdy): this means npn and spdy are enabled. In
+  // case server supports spdy, browser will use spdy.
+  // group B (_npn_with_http): this means npn is enabled but spdy
+  // won't be used. Http is still used for all requests.
+  // default group: no npn or spdy is involved. The "old" non-spdy chrome
+  // behavior.
+  bool is_spdy_trial = false;
+  if (parsed_command_line.HasSwitch(switches::kUseSpdy)) {
+    std::string spdy_mode =
+        parsed_command_line.GetSwitchValueASCII(switches::kUseSpdy);
+    net::HttpNetworkLayer::EnableSpdy(spdy_mode);
+  } else {
+    const FieldTrial::Probability kSpdyDivisor = 1000;
+    // TODO(lzheng): Increase these values to enable more spdy tests.
+    // To enable 100% npn_with_spdy, set kNpnHttpProbability = 0 and set
+    // kNpnSpdyProbability = FieldTrial::kAllRemainingProbability.
+    const FieldTrial::Probability kNpnHttpProbability = 0;  // 0.0%
+    const FieldTrial::Probability kNpnSpdyProbability = 0;  // 0.0%
+    scoped_refptr<FieldTrial> trial =
+        new FieldTrial("SpdyImpact", kSpdyDivisor);
+    // npn with only http support, no spdy.
+    int npn_http_grp =
+        trial->AppendGroup("_npn_with_http", kNpnHttpProbability);
+    // npn with spdy support.
+    int npn_spdy_grp =
+        trial->AppendGroup("_npn_with_spdy", kNpnSpdyProbability);
+    int trial_grp = trial->group();
+    if (trial_grp == npn_http_grp) {
+      is_spdy_trial = true;
+      net::HttpNetworkLayer::EnableSpdy("npn-http");
+    } else if (trial_grp == npn_spdy_grp) {
+      is_spdy_trial = true;
+      net::HttpNetworkLayer::EnableSpdy("npn");
+    } else {
+      CHECK(!is_spdy_trial);
+    }
+  }
+
 #if defined(OS_WIN)
   if (!parsed_command_line.HasSwitch(switches::kUseSChannel) ||
-      parsed_command_line.HasSwitch(switches::kUseSpdy)) {
+      parsed_command_line.HasSwitch(switches::kUseSpdy) ||
+      is_spdy_trial) {
     net::ClientSocketFactory::SetSSLClientSocketFactory(
         net::SSLClientSocketNSSFactory);
     // We want to be sure to init NSPR on the main thread.
@@ -727,9 +771,6 @@ int BrowserMain(const MainFunctionParams& parameters) {
   SystemMonitor system_monitor;
   HighResolutionTimerManager hi_res_timer_manager;
 
-  // Initialize statistical testing infrastructure for entire browser.
-  FieldTrialList field_trial;
-
   std::wstring app_name = chrome::kBrowserAppName;
   std::string thread_name_string = WideToASCII(app_name + L"_BrowserMain");
 
diff --git a/chrome/browser/renderer_host/resource_dispatcher_host.cc b/chrome/browser/renderer_host/resource_dispatcher_host.cc
index 17bdf4e..580c2c2 100644
--- a/chrome/browser/renderer_host/resource_dispatcher_host.cc
+++ b/chrome/browser/renderer_host/resource_dispatcher_host.cc
@@ -163,6 +163,7 @@ void PopulateResourceResponse(URLRequest* request,
   request->GetMimeType(&response->response_head.mime_type);
   response->response_head.was_fetched_via_spdy =
       request->was_fetched_via_spdy();
+  response->response_head.was_npn_negotiated = request->was_npn_negotiated();
   appcache::AppCacheInterceptor::GetExtraResponseInfo(
       request,
       &response->response_head.appcache_id,
diff --git a/chrome/common/render_messages.h b/chrome/common/render_messages.h
index e1f8791..ab0dcc1 100644
--- a/chrome/common/render_messages.h
+++ b/chrome/common/render_messages.h
@@ -1327,6 +1327,7 @@ struct ParamTraits<webkit_glue::ResourceLoaderBridge::ResponseInfo> {
     WriteParam(m, p.appcache_id);
     WriteParam(m, p.appcache_manifest_url);
     WriteParam(m, p.was_fetched_via_spdy);
+    WriteParam(m, p.was_npn_negotiated);
   }
   static bool Read(const Message* m, void** iter, param_type* r) {
     return
@@ -1339,7 +1340,8 @@ struct ParamTraits<webkit_glue::ResourceLoaderBridge::ResponseInfo> {
       ReadParam(m, iter, &r->content_length) &&
       ReadParam(m, iter, &r->appcache_id) &&
       ReadParam(m, iter, &r->appcache_manifest_url) &&
-      ReadParam(m, iter, &r->was_fetched_via_spdy);
+      ReadParam(m, iter, &r->was_fetched_via_spdy) &&
+      ReadParam(m, iter, &r->was_npn_negotiated);
   }
   static void Log(const param_type& p, std::wstring* l) {
     l->append(L"(");
@@ -1362,6 +1364,8 @@ struct ParamTraits<webkit_glue::ResourceLoaderBridge::ResponseInfo> {
     LogParam(p.appcache_manifest_url, l);
     l->append(L", ");
     LogParam(p.was_fetched_via_spdy, l);
+    l->append(L",");
+    LogParam(p.was_npn_negotiated, l);
     l->append(L")");
   }
 };
diff --git a/chrome/renderer/loadtimes_extension_bindings.cc b/chrome/renderer/loadtimes_extension_bindings.cc
index c43cd95..151e78d 100644
--- a/chrome/renderer/loadtimes_extension_bindings.cc
+++ b/chrome/renderer/loadtimes_extension_bindings.cc
@@ -131,6 +131,9 @@ class LoadTimesExtensionWrapper : public v8::Extension {
         load_times->Set(
             v8::String::New("wasFetchedViaSpdy"),
             v8::Boolean::New(navigation_state->was_fetched_via_spdy()));
+        load_times->Set(
+            v8::String::New("wasNpnNegotiated"),
+            v8::Boolean::New(navigation_state->was_npn_negotiated()));
         return load_times;
       }
     }
diff --git a/chrome/renderer/navigation_state.h b/chrome/renderer/navigation_state.h
index 36a8441..8d762aa 100644
--- a/chrome/renderer/navigation_state.h
+++ b/chrome/renderer/navigation_state.h
@@ -220,6 +220,9 @@ class NavigationState : public WebKit::WebDataSource::ExtraData {
   void set_was_fetched_via_spdy(bool value) { was_fetched_via_spdy_ = value; }
   bool was_fetched_via_spdy() const { return was_fetched_via_spdy_; }
 
+  void set_was_npn_negotiated(bool value) { was_npn_negotiated_ = value; }
+  bool was_npn_negotiated() const { return was_npn_negotiated_; }
+
   // Whether the frame text contents was translated to a different language.
   void set_was_translated(bool value) { was_translated_ = value; }
   bool was_translated() const { return was_translated_; }
@@ -243,6 +246,7 @@ class NavigationState : public WebKit::WebDataSource::ExtraData {
         cache_policy_override_(WebKit::WebURLRequest::UseProtocolCachePolicy),
         user_script_idle_scheduler_(NULL),
         was_fetched_via_spdy_(false),
+        was_npn_negotiated_(false),
         was_translated_(false) {
   }
 
@@ -275,6 +279,8 @@ class NavigationState : public WebKit::WebDataSource::ExtraData {
 
   bool was_fetched_via_spdy_;
 
+  bool was_npn_negotiated_;
+
   bool was_translated_;
 
   DISALLOW_COPY_AND_ASSIGN(NavigationState);
diff --git a/chrome/renderer/render_view.cc b/chrome/renderer/render_view.cc
index 09c3436..45e2c37 100644
--- a/chrome/renderer/render_view.cc
+++ b/chrome/renderer/render_view.cc
@@ -2875,13 +2875,20 @@ void RenderView::didReceiveResponse(
   if (frame->isViewSourceModeEnabled())
     return;
 
+  NavigationState* navigation_state =
+      NavigationState::FromDataSource(frame->provisionalDataSource());
+  CHECK(navigation_state);
+
   // Record that this was a page loaded over SPDY.
   if (response.wasFetchedViaSPDY()) {
-    NavigationState* navigation_state =
-        NavigationState::FromDataSource(frame->provisionalDataSource());
     navigation_state->set_was_fetched_via_spdy(true);
   }
 
+  // Record that npn protocol was negotiated when fetching this page.
+  if (response.wasNpnNegotiated()) {
+    navigation_state->set_was_npn_negotiated(true);
+  }
+
   // Consider loading an alternate error page for 404 responses.
   if (response.httpStatusCode() != 404)
     return;
@@ -2890,8 +2897,6 @@ void RenderView::didReceiveResponse(
   if (!GetAlternateErrorPageURL(response.url(), HTTP_404).is_valid())
     return;
 
-  NavigationState* navigation_state =
-      NavigationState::FromDataSource(frame->provisionalDataSource());
   navigation_state->set_postpone_loading_data(true);
   navigation_state->clear_postponed_data();
 }
@@ -4556,6 +4561,27 @@ void RenderView::DumpLoadHistograms() const {
         begin_to_finish_doc, kBeginToFinishDocMin, kBeginToFinishDocMax,
         kBeginToFinishDocBucketCount);
 
+  static bool use_spdy_histogram(FieldTrialList::Find("SpdyImpact") &&
+      !FieldTrialList::Find("SpdyImpact")->group_name().empty());
+  if (use_spdy_histogram) {
+    switch (load_type) {
+      case NavigationState::LINK_LOAD_NORMAL:
+        if (navigation_state->was_npn_negotiated()) {
+          DCHECK(FieldTrialList::Find("SpdyImpact")->group_name() ==
+                 "_npn_with_http" ||
+                 FieldTrialList::Find("SpdyImpact")->group_name() ==
+                 "_npn_with_spdy");
+          UMA_HISTOGRAM_CUSTOM_TIMES(FieldTrial::MakeName(
+              "Renderer4.BeginToFinish_LinkLoadNormal_SpdyTrial", "SpdyImpact"),
+              begin_to_finish, kBeginToFinishMin, kBeginToFinishMax,
+              kBeginToFinishBucketCount);
+        }
+        break;
+      default:
+        break;
+    }
+  }
+
   UMA_HISTOGRAM_CUSTOM_TIMES("Renderer4.StartToFinish",
       finish - start, kBeginToFinishMin,
       kBeginToFinishMax, kBeginToFinishBucketCount);