Cleanup the Win overlapped reads vs. non-blocking reads by removing the overlapped read code path

chrome/renderer/page_load_histograms.cc

Index: chrome/renderer/page_load_histograms.cc
===================================================================
--- chrome/renderer/page_load_histograms.cc	(revision 215603)
+++ chrome/renderer/page_load_histograms.cc	(working copy)
@@ -728,43 +728,6 @@
     }
   }
 
-  // Histograms to determine if disabling overlapped TCP reads
-  // has an impact on PLT.
-  static const bool use_overlapped_read_histogram =
-      base::FieldTrialList::TrialExists("OverlappedReadImpact");
-  if (use_overlapped_read_histogram) {
-    UMA_HISTOGRAM_ENUMERATION(
-        base::FieldTrial::MakeName("PLT.Abandoned", "OverlappedReadImpact"),
-        abandoned_page ? 1 : 0, 2);
-    UMA_HISTOGRAM_ENUMERATION(
-        base::FieldTrial::MakeName("PLT.LoadType", "OverlappedReadImpact"),
-        load_type, DocumentState::kLoadTypeMax);
-    switch (load_type) {
-      case DocumentState::NORMAL_LOAD:
-        PLT_HISTOGRAM(base::FieldTrial::MakeName(
-            "PLT.BeginToFinish_NormalLoad", "OverlappedReadImpact"),
-            begin_to_finish_all_loads);
-        break;
-      case DocumentState::LINK_LOAD_NORMAL:
-        PLT_HISTOGRAM(base::FieldTrial::MakeName(
-            "PLT.BeginToFinish_LinkLoadNormal", "OverlappedReadImpact"),
-            begin_to_finish_all_loads);
-        break;
-      case DocumentState::LINK_LOAD_RELOAD:
-        PLT_HISTOGRAM(base::FieldTrial::MakeName(
-            "PLT.BeginToFinish_LinkLoadReload", "OverlappedReadImpact"),
-            begin_to_finish_all_loads);
-        break;
-      case DocumentState::LINK_LOAD_CACHE_STALE_OK:
-        PLT_HISTOGRAM(base::FieldTrial::MakeName(
-            "PLT.BeginToFinish_LinkLoadStaleOk", "OverlappedReadImpact"),
-            begin_to_finish_all_loads);
-        break;
-      default:
-        break;
-    }
-  }
-
   // Site isolation metrics.
   UMA_HISTOGRAM_COUNTS("SiteIsolation.PageLoadsWithCrossSiteFrameAccess",
                        cross_origin_access_count_);