Add virtual layout test for GPU accelerated decoding.

content/shell/app/shell_main_delegate.cc

Index: content/shell/app/shell_main_delegate.cc
diff --git a/content/shell/app/shell_main_delegate.cc b/content/shell/app/shell_main_delegate.cc
index 4d47d23af167f2ffa89dff220ffdb5c213925939..82fa47a6c47744758856ded07268799eee9f3377 100644
--- a/content/shell/app/shell_main_delegate.cc
+++ b/content/shell/app/shell_main_delegate.cc
@@ -167,7 +167,8 @@ bool ShellMainDelegate::BasicStartupComplete(int* exit_code) {
     command_line.AppendSwitch(switches::kEnableLogging);
     command_line.AppendSwitch(switches::kAllowFileAccessFromFiles);
     // only default to osmesa if the flag isn't already specified.
-    if (!command_line.HasSwitch(switches::kUseGL)) {
+    if (!command_line.HasSwitch(switches::kUseGpuInTests) &&
+        !command_line.HasSwitch(switches::kUseGL)) {
       command_line.AppendSwitchASCII(switches::kUseGL,
                                      gl::kGLImplementationOSMesaName);
     }