add channel_id in messaging.AndroidNotification (#202)

* add channel_id in messaging.AndroidNotification

* fix lint

Author: chemidy

CHANGELOG.md

@@ -1,5 +1,6 @@
 # Unreleased
 
+- [added] `messaging.AndroidNotification`type now supports channel_id.
 - [dropped] Dropped support for Go 1.8 and earlier.
 - [fixed] Fixing error handling in FCM. The SDK now checks the key 
   `type.googleapis.com/google.firebase.fcm.v1.FcmError` to set error code.

messaging/messaging.go

@@ -215,6 +215,7 @@ type AndroidNotification struct {
 	BodyLocArgs  []string `json:"body_loc_args,omitempty"`
 	TitleLocKey  string   `json:"title_loc_key,omitempty"`
 	TitleLocArgs []string `json:"title_loc_args,omitempty"`
+	ChannelID    string   `json:"channel_id,omitempty"`
 }
 
 // WebpushConfig contains messaging options specific to the WebPush protocol.

messaging/messaging_test.go

@@ -148,6 +148,7 @@ var validMessages = []struct {
 					TitleLocArgs: []string{"t1", "t2"},
 					BodyLocKey:   "blk",
 					BodyLocArgs:  []string{"b1", "b2"},
+					ChannelID:    "channel",
 				},
 				TTL: &ttlWithNanos,
 			},
@@ -165,6 +166,7 @@ var validMessages = []struct {
 					"title_loc_args": []interface{}{"t1", "t2"},
 					"body_loc_key":   "blk",
 					"body_loc_args":  []interface{}{"b1", "b2"},
+					"channel_id":     "channel",
 				},
 				"ttl": "1.500000000s",
 			},