[Findit] Add a sub-pipeline to analyze failures caused by DEPS rolls.

appengine/findit/common/dependency.py

Index: appengine/findit/common/dependency.py
diff --git a/appengine/findit/common/dependency.py b/appengine/findit/common/dependency.py
index 7e6812d9d46efad0cc55bb66ad2f22eba22d39cf..e3216ca0c387657b4884c3cc968d878aa28813f1 100644
--- a/appengine/findit/common/dependency.py
+++ b/appengine/findit/common/dependency.py
@@ -4,8 +4,8 @@
 
 
 class Dependency(object):
-  """Represent a dependency in Chrome, like blink, v8, pdfium, etc."""
-  def __init__(self, path, repo_url, revision, deps_file):
+  """Represents a dependency in Chrome, like blink, v8, pdfium, etc."""
+  def __init__(self, path, repo_url, revision, deps_file='DEPS'):
     self.path = path
     self.repo_url = repo_url
     self.revision = revision
@@ -32,3 +32,22 @@ class Dependency(object):
         'deps_file': self.deps_file,
         'children': children_dict,
     }
+
+
+class DependencyRoll(object):
+  """Represents a dependency roll (revision update) in chromium."""
+  def __init__(self, path, repo_url, old_revision, new_revision):
+    # Note: It is possible that the DEPS roll is a revert so that |new_revision|
+    # is actually older than |old_revision| in the dependency.
+    self.path = path
+    self.repo_url = repo_url
+    self.old_revision = old_revision
+    self.new_revision = new_revision
+
+  def ToDict(self):
+    return {
+        'path': self.path,
+        'repo_url': self.repo_url,
+        'old_revision': self.old_revision,
+        'new_revision': self.new_revision,
+    }