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

1 files changed, 30 insertions, 4 deletions

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);