Rename IFWL_Timer and IFWL_TimerInfo

These twho files are not interfaces. Renamed to be CFWL to signify they are
concrete implementations.

Review-Url: https://codereview.chromium.org/2526513002
diff --git a/BUILD.gn b/BUILD.gn
index 81b2c61..9e58f5a 100644
--- a/BUILD.gn
+++ b/BUILD.gn
@@ -1260,6 +1260,10 @@
       "xfa/fwl/core/cfwl_themepart.cpp",
       "xfa/fwl/core/cfwl_themepart.h",
       "xfa/fwl/core/cfwl_themetext.h",
+      "xfa/fwl/core/cfwl_timer.cpp",
+      "xfa/fwl/core/cfwl_timer.h",
+      "xfa/fwl/core/cfwl_timerinfo.cpp",
+      "xfa/fwl/core/cfwl_timerinfo.h",
       "xfa/fwl/core/cfwl_widget.cpp",
       "xfa/fwl/core/cfwl_widget.h",
       "xfa/fwl/core/cfwl_widgetmgr.cpp",
@@ -1311,10 +1315,6 @@
       "xfa/fwl/core/ifwl_spinbutton.cpp",
       "xfa/fwl/core/ifwl_spinbutton.h",
       "xfa/fwl/core/ifwl_themeprovider.h",
-      "xfa/fwl/core/ifwl_timer.cpp",
-      "xfa/fwl/core/ifwl_timer.h",
-      "xfa/fwl/core/ifwl_timerinfo.cpp",
-      "xfa/fwl/core/ifwl_timerinfo.h",
       "xfa/fwl/core/ifwl_widget.cpp",
       "xfa/fwl/core/ifwl_widget.h",
       "xfa/fwl/core/ifwl_widgetdelegate.h",