[core] Remove Response::Error::Reason::Canceled

There is no such thing as a cancelled response, only cancelled requests. A request that is cancelled does not have its callback called with a Response.

include/mbgl/storage/response.hpp

@@ -38,7 +38,6 @@ public:
         NotFound = 2,
         Server = 3,
         Connection = 4,
-        Canceled = 5,
         Other = 6,
     } reason = Reason::Other;
 

platform/android/src/http_request_android.cpp

@@ -172,6 +172,7 @@ void HTTPAndroidRequest::cancel() {
 
 void HTTPAndroidRequest::finish() {
     if (!cancelled) {
+        assert(response);
         notify(*response);
     }
 
@@ -234,7 +235,7 @@ void HTTPAndroidRequest::onFailure(JNIEnv* env, int type, jstring message) {
             response->error = std::make_unique<Error>(Error::Reason::Server, messageStr);
             break;
         case canceledError:
-            response->error = std::make_unique<Error>(Error::Reason::Canceled, "Request was cancelled");
+            response.reset();
             break;
         default:
             response->error = std::make_unique<Error>(Error::Reason::Other, messageStr);

platform/darwin/http_request_nsurl.mm

@@ -133,7 +133,7 @@ void HTTPNSURLRequest::handleResponse() {
     }
 
     if (!cancelled) {
-        // Actually return the response.
+        assert(response);
         notify(*response);
     }
 
@@ -158,8 +158,8 @@ void HTTPNSURLRequest::handleResult(NSData *data, NSURLResponse *res, NSError *e
 
     if (error) {
         if ([error code] == NSURLErrorCancelled) {
-            response->error =
-                std::make_unique<Error>(Error::Reason::Canceled, "Request was cancelled");
+            response.reset();
+
         } else {
             if (data) {
                 response->data =

test/storage/storage.hpp

@@ -24,7 +24,6 @@ inline std::ostream& operator<<(std::ostream& os, Response::Error::Reason r) {
         case Response::Error::Reason::NotFound: return os << "Response::Error::Reason::NotFound";
         case Response::Error::Reason::Server: return os << "Response::Error::Reason::Server";
         case Response::Error::Reason::Connection: return os << "Response::Error::Reason::Connection";
-        case Response::Error::Reason::Canceled: return os << "Response::Error::Reason::Canceled";
         case Response::Error::Reason::Other: return os << "Response::Error::Reason::Other";
         default: return os << "<Unknown>";
     }