[cast_channel] Move cast_channel related files from //extensions to //components

components/cast_channel/proto/cast_channel.proto

Index: components/cast_channel/proto/cast_channel.proto
diff --git a/extensions/common/api/cast_channel/cast_channel.proto b/components/cast_channel/proto/cast_channel.proto
similarity index 97%
rename from extensions/common/api/cast_channel/cast_channel.proto
rename to components/cast_channel/proto/cast_channel.proto
index 098ecb74dacbaaa5c4f8016ad627acb5a2a278b7..4cac6db606730c144d6430985cd85b50a3127cfd 100644
--- a/extensions/common/api/cast_channel/cast_channel.proto
+++ b/components/cast_channel/proto/cast_channel.proto
@@ -6,14 +6,12 @@ syntax = "proto2";
 
 option optimize_for = LITE_RUNTIME;
 
-package extensions.api.cast_channel;
+package cast_channel;
 
 message CastMessage {
   // Always pass a version of the protocol for future compatibility
   // requirements.
-  enum ProtocolVersion {
-    CASTV2_1_0 = 0;
-  }
+  enum ProtocolVersion { CASTV2_1_0 = 0; }
   required ProtocolVersion protocol_version = 1;
 
   // source and destination ids identify the origin and destination of the