Replace custom blob gRPC API with ByteStream

client/third_party/cachetools/abc.py

+from __future__ import absolute_import
+
+import collections
+
+from abc import abstractmethod
+
+
+class DefaultMapping(collections.MutableMapping):
+
+    __slots__ = ()
+
+    @abstractmethod
+    def __contains__(self, key):  # pragma: nocover
+        return False
+
+    @abstractmethod
+    def __getitem__(self, key):  # pragma: nocover
+        if hasattr(self.__class__, '__missing__'):
+            return self.__class__.__missing__(self, key)
+        else:
+            raise KeyError(key)
+
+    def get(self, key, default=None):
+        if key in self:
+            return self[key]
+        else:
+            return default
+
+    __marker = object()
+
+    def pop(self, key, default=__marker):
+        if key in self:
+            value = self[key]
+            del self[key]
+        elif default is self.__marker:
+            raise KeyError(key)
+        else:
+            value = default
+        return value
+
+    def setdefault(self, key, default=None):
+        if key in self:
+            value = self[key]
+        else:
+            self[key] = value = default
+        return value
+
+DefaultMapping.register(dict)