Make SimpleCache the default backend on ChromeOS/Linux.

chrome/browser/profiles/profile_impl_io_data.cc

Index: chrome/browser/profiles/profile_impl_io_data.cc
diff --git a/chrome/browser/profiles/profile_impl_io_data.cc b/chrome/browser/profiles/profile_impl_io_data.cc
index 49b9a266cc34c2c570e158fc385a849d6c0683b0..d32f939343bba08ecd9fd837fd104fb961cdafc7 100644
--- a/chrome/browser/profiles/profile_impl_io_data.cc
+++ b/chrome/browser/profiles/profile_impl_io_data.cc
@@ -88,12 +88,21 @@ net::BackendType ChooseCacheBackendType() {
   }
   const std::string experiment_name =
       base::FieldTrialList::FindFullName("SimpleCacheTrial");
+#if defined(OS_LINUX) || defined(OS_CHROMEOS)
+  // TODO(gavinp): Remove this experiment in the m53 timeframe.
+  if (experiment_name == "ExperimentNo" ||
+      experiment_name == "ExperimentControl") {

[Alexei Svitkine (slow), 2016/05/13 18:40:51]

If enabled is the new behavior, then any experiment that changes this should
have control group specify the new behavior.

Also, suggests changing the check to StartsWith() per our best practices. You
can also change the one below to be StartsWith() "ExperimentYes" to avoid
needing the two =='s.

[gavinp, 2016/05/13 19:03:39]

Good point. I've renamed the group "Disable" for the new world with Simple Cache
everywhere.
Done.

+    return net::CACHE_BACKEND_BLOCKFILE;
+  }
+  return net::CACHE_BACKEND_SIMPLE;
+#else
   if (experiment_name == "ExperimentYes" ||
       experiment_name == "ExperimentYes2") {
     return net::CACHE_BACKEND_SIMPLE;
   }
   return net::CACHE_BACKEND_BLOCKFILE;
-#endif
+#endif  // #if defined(OS_LINUX) || defined(OS_CHROMEOS)
+#endif  // #if defined(OS_ANDROID)
 }
 
 }  // namespace