Pass mojo_shell args to child processes.

mojo/shell/child_process_host.cc

Index: mojo/shell/child_process_host.cc
diff --git a/mojo/shell/child_process_host.cc b/mojo/shell/child_process_host.cc
index 5f9dbfdacc05d833daa338c404254695d0747fa9..787233cb8c71bea45d1a10066f94d0e5d1ed0434 100644
--- a/mojo/shell/child_process_host.cc
+++ b/mojo/shell/child_process_host.cc
@@ -22,6 +22,7 @@
 #include "mojo/shell/context.h"
 #include "mojo/shell/switches.h"
 #include "mojo/shell/task_runners.h"
+#include "ui/gl/gl_switches.h"
 
 namespace mojo {
 namespace shell {
@@ -97,7 +98,10 @@ void ChildProcessHost::DidStart(bool success) {
 
 bool ChildProcessHost::DoLaunch() {
   static const char* kForwardSwitches[] = {
-      switches::kTraceToConsole, switches::kV, switches::kVModule,
+      switches::kOverrideUseGLWithOSMesaForTests,
+      switches::kTraceToConsole,
+      switches::kV,
+      switches::kVModule,
   };
 
   const base::CommandLine* parent_command_line =
@@ -116,6 +120,10 @@ bool ChildProcessHost::DoLaunch() {
       child_command_line.AppendSwitch(switches::kWaitForDebugger);
   }
 
+  auto args = parent_command_line->GetArgs();
+  for (const auto& arg : args)
+    child_command_line.AppendArgNative(arg);
+
   embedder::HandlePassingInformation handle_passing_info;
   platform_channel_pair_.PrepareToPassClientHandleToChildProcess(
       &child_command_line, &handle_passing_info);