infra_paths module: swarmbucket config

add infra_swarmbucket config for infra_paths module to override
git_cache. The value of path_config property value will be specified by
kitchen.

This will still delete cache every time. The goal of this change is to
fix build.git swarmbucket builds.

TBR=dnj@chromium.org
BUG=

Review-Url: https://codereview.chromium.org/2176913002

recipe_modules/infra_paths/example.expected/paths_swarmbucket_linux.json

+[
+  {
+    "cmd": [],
+    "name": "show cache path",
+    "~followup_annotations": [
+      "@@@STEP_TEXT@[CACHE]@@@"
+    ]
+  },
+  {
+    "name": "$result",
+    "recipe_result": null,
+    "status_code": 0
+  }
+]
\ No newline at end of file

recipe_modules/infra_paths/example.expected/paths_swarmbucket_mac.json

+[
+  {
+    "cmd": [],
+    "name": "show cache path",
+    "~followup_annotations": [
+      "@@@STEP_TEXT@[CACHE]@@@"
+    ]
+  },
+  {
+    "name": "$result",
+    "recipe_result": null,
+    "status_code": 0
+  }
+]
\ No newline at end of file

recipe_modules/infra_paths/example.expected/paths_swarmbucket_win.json

+[
+  {
+    "cmd": [],
+    "name": "show cache path",
+    "~followup_annotations": [
+      "@@@STEP_TEXT@[CACHE]@@@"
+    ]
+  },
+  {
+    "name": "$result",
+    "recipe_result": null,
+    "status_code": 0
+  }
+]
\ No newline at end of file

recipe_modules/infra_paths/example.py

@@ -20,7 +20,7 @@ def GenTests(api):
   yield api.test('basic')
 
   for platform in ('linux', 'mac', 'win'):
-    for path_config in ('buildbot', 'kitchen'):
+    for path_config in ('buildbot', 'kitchen', 'swarmbucket'):
       yield (
           api.test('paths_%s_%s' % (path_config, platform)) +
           api.platform.name(platform) +

recipe_modules/infra_paths/path_config.py

@@ -51,3 +51,8 @@ def infra_kitchen(c):
     c.base_paths['git_cache'] = c.base_paths['root'] + ('cache_dir',)
     for path in ('goma_cache', 'goma_deps_cache'):
       c.base_paths[path] = c.base_paths['cache'] + (path,)
+
+
+@CONFIG_CTX(includes=['infra_buildbot'])
+def infra_swarmbucket(c):
+  c.base_paths['git_cache'] = c.base_paths['root'] + ('git_cache',)