Run the WebGL conformance tests with the passthrough command decoder.

gpu/ipc/service/gpu_init.cc

Index: gpu/ipc/service/gpu_init.cc
diff --git a/gpu/ipc/service/gpu_init.cc b/gpu/ipc/service/gpu_init.cc
index 1e912037747c8dac81c404268660827e6d382f92..98620c4ece9ee668c52299a48edb56cb1f6dad09 100644
--- a/gpu/ipc/service/gpu_init.cc
+++ b/gpu/ipc/service/gpu_init.cc
@@ -158,6 +158,9 @@ bool GpuInit::InitializeAndStartSandbox(const base::CommandLine& command_line) {
 #endif
   gpu_info_.in_process_gpu = false;
 
+  gpu_info_.passthrough_cmd_decoder =
+      command_line.HasSwitch(switches::kUsePassthroughCmdDecoder);
+
   sandbox_helper_->PreSandboxStartup();
 
 #if defined(OS_LINUX)