skydb shouldn't use origin on Linux

Unfortunately, using --origin on Linux is slow and too painful to use at the
moment. We should work on fixing that, but currently many of us have this in
our local working copy anyway.

R=eseidel@chromium.org

Review URL: https://codereview.chromium.org/922823002

engine/src/flutter/tools/skydb

@@ -118,7 +118,11 @@ class SkyDebugger(object):
             remote_server_port,
             self.pids['sky_server_root'],
             self.pids['build_dir'])
-        shell_args += ['--origin=%s' % build_dir_url]
+
+        # TODO(eseidel): We should do this on linux, but we need to fix
+        # mojo http loading to be faster first.
+        if is_android:
+            shell_args += ['--origin=%s' % build_dir_url]
 
         # Desktop-only work-around for mojo crashing under chromoting.
         if not is_android and args.use_osmesa:
@@ -194,6 +198,8 @@ class SkyDebugger(object):
         self.pids['sky_command_port'] = args.command_port
 
         if is_android:
+            # TODO(eseidel): This should move into a helper method and handle
+            # failures with nice messages explaining how to get root.
             subprocess.check_call([ADB_PATH, 'root'])
 
             # We could make installing conditional on an argument.