Delete long-expired GlobalSdch field trial.

chrome/renderer/page_load_histograms.cc

Index: chrome/renderer/page_load_histograms.cc
===================================================================
--- chrome/renderer/page_load_histograms.cc	(revision 202453)
+++ chrome/renderer/page_load_histograms.cc	(working copy)
@@ -416,34 +416,28 @@
   static const bool use_sdch_histogram =
       base::FieldTrialList::TrialExists("GlobalSdch");
   if (use_sdch_histogram) {
-    UMA_HISTOGRAM_ENUMERATION(
-        base::FieldTrial::MakeName("PLT.LoadType", "GlobalSdch"),
-        load_type, DocumentState::kLoadTypeMax);
+    UMA_HISTOGRAM_ENUMERATION("PLT.LoadType", load_type,
+                              DocumentState::kLoadTypeMax);
     switch (load_type) {
       case DocumentState::NORMAL_LOAD:
-        PLT_HISTOGRAM(base::FieldTrial::MakeName(
-            "PLT.BeginToFinish_NormalLoad", "GlobalSdch"),
-            begin_to_finish_all_loads);
+        PLT_HISTOGRAM("PLT.BeginToFinish_NormalLoad",

[jar (doing other things), 2013/05/28 18:35:02]

You'll notice that this exact histogram is already gathered on line 364.

This whole section, starting at line 418, and ending at line 445, is *only* done
*IF* we have a field trial.  IF we don't have a field trial, then we don't do
the MakeName combination.

Bottom line: You should remove all code from line 414 to line 445 when you rip
out the field trial.

The pattern seen here is VERY common, and consists of:

a) Check to see if there is a histogram of the given name.
b) If there is one, then record some special variants on *existing* histograms,
using the MakeName() helper.

[Alexei Svitkine (slow), 2013/05/28 18:48:58]

Ah, you're absolutely right! Done.

+                      begin_to_finish_all_loads);
         break;
       case DocumentState::LINK_LOAD_NORMAL:
-        PLT_HISTOGRAM(base::FieldTrial::MakeName(
-            "PLT.BeginToFinish_LinkLoadNormal", "GlobalSdch"),
-            begin_to_finish_all_loads);
+        PLT_HISTOGRAM("PLT.BeginToFinish_LinkLoadNormal",
+                      begin_to_finish_all_loads);
         break;
       case DocumentState::LINK_LOAD_RELOAD:
-        PLT_HISTOGRAM(base::FieldTrial::MakeName(
-            "PLT.BeginToFinish_LinkLoadReload", "GlobalSdch"),
-            begin_to_finish_all_loads);
+        PLT_HISTOGRAM("PLT.BeginToFinish_LinkLoadReload",
+                      begin_to_finish_all_loads);
         break;
       case DocumentState::LINK_LOAD_CACHE_STALE_OK:
-        PLT_HISTOGRAM(base::FieldTrial::MakeName(
-            "PLT.BeginToFinish_LinkLoadStaleOk", "GlobalSdch"),
-            begin_to_finish_all_loads);
+        PLT_HISTOGRAM("PLT.BeginToFinish_LinkLoadStaleOk",
+                      begin_to_finish_all_loads);
         break;
       case DocumentState::LINK_LOAD_CACHE_ONLY:
-        PLT_HISTOGRAM(base::FieldTrial::MakeName(
-            "PLT.BeginToFinish_LinkLoadCacheOnly", "GlobalSdch"),
-            begin_to_finish_all_loads);
+        PLT_HISTOGRAM("PLT.BeginToFinish_LinkLoadCacheOnly",
+                      begin_to_finish_all_loads);
         break;
       default:
         break;