feat: Channel enum is added

PiperOrigin-RevId: 572916805

google/shopping/type/types.proto

@@ -27,6 +27,8 @@ message Price {
   // The price represented as a number in micros (1 million micros is an
   // equivalent to one's currency standard unit, for example, 1 USD = 1000000
   // micros).
+  // This field can also be set as infinity by setting to -1.
+  // This field only support -1 and positive value.
   optional int64 amount_micros = 1;
 
   // The currency of the price using three-letter acronyms according to [ISO
@@ -140,3 +142,20 @@ message ReportingContext {
     LOCAL_CLOUD_RETAIL = 12;
   }
 }
+
+// [Channel](https://support.google.com/merchants/answer/7361332) of a product.
+//
+// Channel is used to distinguish between online and local products.
+message Channel {
+  // Channel values.
+  enum ChannelEnum {
+    // Not specified.
+    CHANNEL_ENUM_UNSPECIFIED = 0;
+
+    // Online product.
+    ONLINE = 1;
+
+    // Local product.
+    LOCAL = 2;
+  }
+}