tools/benchmarks: Fix failures in image decoding measurements.

cc/base/switches.cc

Index: cc/base/switches.cc
diff --git a/cc/base/switches.cc b/cc/base/switches.cc
index f4aff0cf2cf3c4a03da108e4e951eb630e736fe0..0d0e13b1b2960a501284d4f2e35542796ff8e35f 100644
--- a/cc/base/switches.cc
+++ b/cc/base/switches.cc
@@ -27,6 +27,9 @@ const char kEnableMainFrameBeforeActivation[] =
 // Enables defering image decodes to the image decode service.
 const char kEnableCheckerImaging[] = "enable-checker-imaging";
 
+// Disabled defering image decodes to the image decode service.
+const char kDisableCheckerImaging[] = "disable-checker-imaging";
+
 // Percentage of the browser controls need to be hidden before they will auto
 // hide.
 const char kBrowserControlsHideThreshold[] = "top-controls-hide-threshold";