Add command line switches and about:flag to enable FPS indicator and compositor layer tree.

chrome/browser/about_flags.cc

Index: chrome/browser/about_flags.cc
diff --git a/chrome/browser/about_flags.cc b/chrome/browser/about_flags.cc
index 4f6999fd4d48d7cc439b4c36b4db9204bb1ae5bb..cfc87e9eebea3c25fa806f6c0c0b6c8edc73d9fa 100644
--- a/chrome/browser/about_flags.cc
+++ b/chrome/browser/about_flags.cc
@@ -155,6 +155,13 @@ const Experiment kExperiments[] = {
     SINGLE_VALUE_TYPE(switches::kShowCompositedLayerBorders)
   },
   {
+    "show-fps-counter",
+    IDS_FLAGS_SHOW_FPS_COUNTER,
+    IDS_FLAGS_SHOW_FPS_COUNTER_DESCRIPTION,
+    kOsAll,
+    SINGLE_VALUE_TYPE(switches::kShowFPSCounter)
+  },
+  {
     "gpu-canvas-2d",  // FLAGS:RECORD_UMA
     IDS_FLAGS_ACCELERATED_CANVAS_2D_NAME,
     IDS_FLAGS_ACCELERATED_CANVAS_2D_DESCRIPTION,