Revert of Simplify mojo_shell since it's now only used for Mandoline.

mojo/services/html_viewer/html_viewer.cc

Index: mojo/services/html_viewer/html_viewer.cc
diff --git a/mojo/services/html_viewer/html_viewer.cc b/mojo/services/html_viewer/html_viewer.cc
index 201343c2712b254cfa76e69e32fd108f256fb8ae..abe6379a7d2990892c0444a47ac653a6473f995b 100644
--- a/mojo/services/html_viewer/html_viewer.cc
+++ b/mojo/services/html_viewer/html_viewer.cc
@@ -44,7 +44,8 @@ using mojo::URLResponsePtr;
 
 namespace html_viewer {
 
-// Switches for html_viewer.
+// Switches for html_viewer to be used with "--args-for". For example:
+// --args-for='mojo:html_viewer --enable-mojo-media-renderer'
 
 // Enable MediaRenderer in media pipeline instead of using the internal
 // media::Renderer implementation.
@@ -182,7 +183,16 @@ class HTMLViewer : public mojo::ApplicationDelegate,
 
     ui::RegisterPathProvider();
 
+    base::CommandLine::StringVector command_line_args;
+#if defined(OS_WIN)
+    for (const auto& arg : app->args())
+      command_line_args.push_back(base::UTF8ToUTF16(arg));
+#elif defined(OS_POSIX)
+    command_line_args = app->args();
+#endif
+
     base::CommandLine* command_line = base::CommandLine::ForCurrentProcess();
+    command_line->InitFromArgv(command_line_args);
 
     logging::LoggingSettings settings;
     settings.logging_dest = logging::LOG_TO_SYSTEM_DEBUG_LOG;