add GDrive provider support (#118)

* GDrive provider support
* More reliable basedir ownership
* Fix mimetype

vendor/cloud.google.com/go/firestore/writebatch.go

@@ -0,0 +1,82 @@
+// Copyright 2017 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package firestore
+
+import (
+	"errors"
+
+	pb "google.golang.org/genproto/googleapis/firestore/v1beta1"
+
+	"golang.org/x/net/context"
+)
+
+// A WriteBatch holds multiple database updates. Build a batch with the Create, Set,
+// Update and Delete methods, then run it with the Commit method. Errors in Create,
+// Set, Update or Delete are recorded instead of being returned immediately. The
+// first such error is returned by Commit.
+type WriteBatch struct {
+	c      *Client
+	err    error
+	writes []*pb.Write
+}
+
+func (b *WriteBatch) add(ws []*pb.Write, err error) *WriteBatch {
+	if b.err != nil {
+		return b
+	}
+	if err != nil {
+		b.err = err
+		return b
+	}
+	b.writes = append(b.writes, ws...)
+	return b
+}
+
+// Create adds a Create operation to the batch.
+// See DocumentRef.Create for details.
+func (b *WriteBatch) Create(dr *DocumentRef, data interface{}) *WriteBatch {
+	return b.add(dr.newCreateWrites(data))
+}
+
+// Set adds a Set operation to the batch.
+// See DocumentRef.Set for details.
+func (b *WriteBatch) Set(dr *DocumentRef, data interface{}, opts ...SetOption) *WriteBatch {
+	return b.add(dr.newSetWrites(data, opts))
+}
+
+// Delete adds a Delete operation to the batch.
+// See DocumentRef.Delete for details.
+func (b *WriteBatch) Delete(dr *DocumentRef, opts ...Precondition) *WriteBatch {
+	return b.add(dr.newDeleteWrites(opts))
+}
+
+// Update adds an Update operation to the batch.
+// See DocumentRef.Update for details.
+func (b *WriteBatch) Update(dr *DocumentRef, data []Update, opts ...Precondition) *WriteBatch {
+	return b.add(dr.newUpdatePathWrites(data, opts))
+}
+
+// Commit applies all the writes in the batch to the database atomically. Commit
+// returns an error if there are no writes in the batch, if any errors occurred in
+// constructing the writes, or if the Commmit operation fails.
+func (b *WriteBatch) Commit(ctx context.Context) ([]*WriteResult, error) {
+	if b.err != nil {
+		return nil, b.err
+	}
+	if len(b.writes) == 0 {
+		return nil, errors.New("firestore: cannot commit empty WriteBatch")
+	}
+	return b.c.commit(ctx, b.writes)
+}