Disable moz, dhtml, and roborhornet_pro benchmarks on all OSes except Chrome OS

tools/perf/benchmarks/page_cycler.py

Index: tools/perf/benchmarks/page_cycler.py
diff --git a/tools/perf/benchmarks/page_cycler.py b/tools/perf/benchmarks/page_cycler.py
index 73c1ad4b6213d588310a61c9d240e56610dc69be..d1ce410fac3c3ef368ec41cd1fcd4b5cf9b9a9ea 100644
--- a/tools/perf/benchmarks/page_cycler.py
+++ b/tools/perf/benchmarks/page_cycler.py
@@ -32,6 +32,9 @@ class _PageCycler(benchmark.Benchmark):
         report_speed_index = options.report_speed_index)
 
 
+# This is an old page set, we intend to remove it after more modern benchmarks
+# work on CrOS.
+@benchmark.Enabled('chromeos')
 class PageCyclerDhtml(_PageCycler):
   page_set = page_sets.DhtmlPageSet
 
@@ -63,6 +66,9 @@ class PageCyclerMorejs(_PageCycler):
   page_set = page_sets.MorejsPageSet
 
 
+# This is an old page set, we intend to remove it after more modern benchmarks
+# work on CrOS.
+@benchmark.Enabled('chromeos')
 class PageCyclerMoz(_PageCycler):
   page_set = page_sets.MozPageSet