Add step generator protocol, remove annotated_checkout, remove script.

scripts/slave/recipes_test/run_presubmit.chromium.expected

 [
-  {
-    "cmd": [
-      "[DEPOT_TOOLS_ROOT]/apply_issue", 
-      "-r", 
-      "[BUILD_ROOT]/slave/fake_slave/build/src/", 
-      "-i", 
-      12853011, 
-      "-p", 
-      1, 
-      "-s", 
-      "https://chromiumcodereview.appspot.com", 
-      "-e", 
-      "commit-bot@chromium.org"
-    ], 
-    "name": "apply_issue"
-  }, 
-  {
-    "cmd": [
-      "[DEPOT_TOOLS_ROOT]/presubmit_support.py", 
-      "--root", 
-      "[BUILD_ROOT]/slave/fake_slave/build/src/", 
-      "--commit", 
-      "--verbose", 
-      "--verbose", 
-      "--issue", 
-      12853011, 
-      "--patchset", 
-      1, 
-      "--skip_canned", 
-      "CheckRietveldTryJobExecution", 
-      "--skip_canned", 
-      "CheckTreeIsOpen", 
-      "--skip_canned", 
-      "CheckBuildbotPendingBuilds", 
-      "--rietveld_url", 
-      "https://chromiumcodereview.appspot.com", 
-      "--rietveld_email", 
-      "", 
-      "--rietveld_fetch"
-    ], 
-    "name": "presubmit"
-  }
+  {"cmd": ["[DEPOT_TOOLS_ROOT]/gclient", "config", "--spec", "solutions = [{'managed': True, 'custom_vars': {'webkit_trunk': 'svn://svn-mirror.golo.chromium.org/blink/trunk', 'googlecode_url': 'svn://svn-mirror.golo.chromium.org/%s', 'nacl_trunk': 'http://src.chromium.org/native_client/trunk', 'sourceforge_url': 'svn://svn-mirror.golo.chromium.org/%(repo)s'}, 'url': 'svn://svn-mirror.golo.chromium.org/chrome/trunk/src', 'custom_deps': {'src/third_party/WebKit/LayoutTests': None, 'src/webkit/data/layout_tests/LayoutTests': None}, 'deps_file': 'DEPS', 'safesync_url': '', 'name': 'src'}]\n"], "name": "gclient setup", "seed_steps": ["gclient setup", "gclient clean", "gclient sync"]},
+  {"cmd": ["[DEPOT_TOOLS_ROOT]/gclient", "revert", "--nohooks"], "name": "gclient clean"},
+  {"cmd": ["[DEPOT_TOOLS_ROOT]/gclient", "sync", "--nohooks"], "name": "gclient sync"},
+  {"cmd": ["[DEPOT_TOOLS_ROOT]/apply_issue", "-r", "[SLAVE_BUILD_ROOT]/src/", "-i", 12853011, "-p", 1, "-s", "https://chromiumcodereview.appspot.com", "-e", "commit-bot@chromium.org"], "name": "apply_issue"},
+  {"cmd": ["[DEPOT_TOOLS_ROOT]/presubmit_support.py", "--root", "[SLAVE_BUILD_ROOT]/src/", "--commit", "--verbose", "--verbose", "--issue", 12853011, "--patchset", 1, "--skip_canned", "CheckRietveldTryJobExecution", "--skip_canned", "CheckTreeIsOpen", "--skip_canned", "CheckBuildbotPendingBuilds", "--rietveld_url", "https://chromiumcodereview.appspot.com", "--rietveld_email", "", "--rietveld_fetch"], "name": "presubmit"}
 ]