Generalize patch_project to patch root conversion.

recipe_modules/gclient/api.py

Index: recipe_modules/gclient/api.py
diff --git a/recipe_modules/gclient/api.py b/recipe_modules/gclient/api.py
index 2d9ed949f5f72d6c78cd16552648245fc63fce81..41d7e14e8855f5083137f3b33b6620ca8e833f0c 100644
--- a/recipe_modules/gclient/api.py
+++ b/recipe_modules/gclient/api.py
@@ -336,3 +336,28 @@ class GclientApi(recipe_api.RecipeApi):
       args=[self.m.path['slave_build']],
       infra_step=True,
     )
+
+  def calculate_patch_root(self, patch_project, gclient_config=None):
+    """Returns path where a patch should be applied to based patch_project.
+
+    Maps "patch_project" to a path of directories relative to checkout's root,
+    which describe where to place the patch.
+
+    For now, considers only first solution (c.solutions[0]), but in theory can
+    be extended to all of them.
+
+    See patch_projects solution config property.
+
+    Returns:
+      Relative path, including solution's root.
+      If patch_project is not given or not recognized, it'll be just first
+      solution root.
+    """
+    cfg = gclient_config or self.c
+    root, _ = cfg.solutions[0].patch_projects.get(patch_project, ('', ''))

[Michael Achenbach, 2016/04/25 09:32:42]

solutions[0] goes away when making the dict global.

[tandrii(chromium), 2016/04/25 11:39:50]

Done.

+    if root:
+      # Note, that c.solutions[i].patch_projects contains patch roots as
+      # /-separated path, which are roots of the respective project repos.
+      return self.m.path.join(*root.split('/'))
+    # Default case - assume patch is for first solution.
+    return cfg.solutions[0].name