POSIX: add command line option to launch renderers in a wrapper

chrome/common/chrome_switches.cc

Index: chrome/common/chrome_switches.cc
diff --git a/chrome/common/chrome_switches.cc b/chrome/common/chrome_switches.cc
index 1e5a6228eb7125ef09a3556256a7ff06a056b134..78ad8d3339a3d7663b1021d14d9eccb785dfd66c 100644
--- a/chrome/common/chrome_switches.cc
+++ b/chrome/common/chrome_switches.cc
@@ -371,4 +371,8 @@ const wchar_t kEnableVideo[]                   = L"enable-video";
 // Pass the name of the current running automated test to Chrome.
 const wchar_t kTestName[]                      = L"test-name";
 
+// On POSIX only: the contents of this flag are prepended to the renderer
+// command line. (Useful values might be "valgrind" or "gdb --args")
+const wchar_t kRendererCmdPrefix[]             = L"renderer-cmd-prefix";
+
 }  // namespace switches