Add chrome_split_dll gyp variable, and duplicate chrome_main_dll target

content/browser/renderer_host/render_process_host_impl.cc

Index: content/browser/renderer_host/render_process_host_impl.cc
diff --git a/content/browser/renderer_host/render_process_host_impl.cc b/content/browser/renderer_host/render_process_host_impl.cc
index 5fdc05b7790632d2ee295ced5e165996501b76ec..e736b6ec5bdb144d14f958253a29bda19f90ddc0 100644
--- a/content/browser/renderer_host/render_process_host_impl.cc
+++ b/content/browser/renderer_host/render_process_host_impl.cc
@@ -496,6 +496,8 @@ bool RenderProcessHostImpl::Init() {
 
   CreateMessageFilters();
 
+  // Single-process mode not supported in split-dll mode.
+#if !defined(CHROME_SPLIT_DLL)
   if (run_renderer_in_process()) {
     // Crank up a thread and run the initialization there.  With the way that
     // messages flow between the browser and renderer, this thread is required
@@ -517,7 +519,9 @@ bool RenderProcessHostImpl::Init() {
     in_process_renderer_->StartWithOptions(options);
 
     OnProcessLaunched();  // Fake a callback that the process is ready.
-  } else {
+  } else
+#endif  // !CHROME_SPLIT_DLL
+  {
     // Build command line for renderer.  We call AppendRendererCommandLine()
     // first so the process type argument will appear first.
     CommandLine* cmd_line = new CommandLine(renderer_path);