Add a command line flag for dumping trace events to VLOG

cc/base/switches.cc

Index: cc/base/switches.cc
diff --git a/cc/base/switches.cc b/cc/base/switches.cc
index cf2e6c5ddc4809ff4bb3ad21690886242a14cf87..c06f18b4aff3398467efe6820764cbba2e8abdb4 100644
--- a/cc/base/switches.cc
+++ b/cc/base/switches.cc
@@ -141,6 +141,13 @@ const char kUIShowOccludingRects[] = "ui-show-occluding-rects";
 const char kShowNonOccludingRects[] = "show-nonoccluding-rects";
 const char kUIShowNonOccludingRects[] = "ui-show-nonoccluding-rects";
 
+// Prevents the layer tree unit tests from timing out.
+const char kCCLayerTreeTestNoTimeout[] = "cc-layer-tree-test-no-timeout";
+
+// Trace events get dumped to stderr for debugging purposes.
+const char kCCUnittestsTraceEventsToStderr[] =
+    "cc-unittests-trace-events-to-stderr";
+
 bool IsImplSidePaintingEnabled() {
   const CommandLine& command_line = *CommandLine::ForCurrentProcess();