[cast_channel] Make cast_channel related files not depend on "cast_channel.h"

extensions/browser/api/cast_channel/cast_channel_api.h

Index: extensions/browser/api/cast_channel/cast_channel_api.h
diff --git a/extensions/browser/api/cast_channel/cast_channel_api.h b/extensions/browser/api/cast_channel/cast_channel_api.h
index c257599da0abc997db1b5bd771a95346cc2bdf88..498ca979538c6c0a5574f2c1203ef25e86954542 100644
--- a/extensions/browser/api/cast_channel/cast_channel_api.h
+++ b/extensions/browser/api/cast_channel/cast_channel_api.h
@@ -12,6 +12,7 @@
 #include "base/macros.h"
 #include "base/memory/ref_counted.h"
 #include "base/threading/thread_checker.h"
+#include "components/cast_channel/cast_channel_type.h"
 #include "extensions/browser/api/api_resource_manager.h"
 #include "extensions/browser/api/async_api_function.h"
 #include "extensions/browser/api/cast_channel/cast_socket.h"
@@ -176,7 +177,7 @@ class CastChannelOpenFunction : public CastChannelAsyncApiFunction {
     ~CastMessageHandler() override;
 
     // CastTransport::Delegate implementation.
-    void OnError(cast_channel::ChannelError error_state) override;
+    void OnError(::cast_channel::ChannelError error_state) override;
     void OnMessage(const cast_channel::CastMessage& message) override;
     void Start() override;
 
@@ -197,7 +198,7 @@ class CastChannelOpenFunction : public CastChannelAsyncApiFunction {
   static net::IPEndPoint* ParseConnectInfo(
       const cast_channel::ConnectInfo& connect_info);
 
-  void OnOpen(cast_channel::ChannelError result);
+  void OnOpen(::cast_channel::ChannelError result);
 
   std::unique_ptr<cast_channel::Open::Params> params_;
   // The id of the newly opened socket.