Add downloadContentHost for download style request in DBTransportBaseHostnameConfig (#381)

Author: jamesyangf

Source/ObjectiveDropboxOfficial/Shared/Handwritten/Networking/DBTransportBaseHostnameConfig.h

@@ -30,6 +30,7 @@ NS_ASSUME_NONNULL_BEGIN
 @property (nonatomic, readonly, copy) NSString *meta;
 @property (nonatomic, readonly, copy) NSString *api;
 @property (nonatomic, readonly, copy) NSString *content;
+@property (nonatomic, readonly, copy) NSString *downloadContent;
 @property (nonatomic, readonly, copy) NSString *notify;
 
 ///
@@ -45,11 +46,12 @@ NS_ASSUME_NONNULL_BEGIN
 /// @param meta the hostname to metaserver
 /// @param api the hostname to api server
 /// @param content the hostname to content server
+/// @param downloadContent the hostname to content server for download style
 /// @param notify the hostname to notify server
 ///
 /// @return An initialized instance with the provided hostname configuration
 ///
-- (instancetype)initWithMeta:(NSString *)meta api:(NSString *)api content:(NSString *)content notify:(NSString *)notify;
+- (instancetype)initWithMeta:(NSString *)meta api:(NSString *)api content:(NSString *)content downloadContent:(NSString *)downloadContent notify:(NSString *)notify;
 
 ///
 /// Returns the prefix to use for API calls to the given route type.

Source/ObjectiveDropboxOfficial/Shared/Handwritten/Networking/DBTransportBaseHostnameConfig.m

@@ -41,17 +41,32 @@ - (instancetype)initWithMeta:(NSString *)meta
     _meta = meta;
     _api = api;
     _content = content;
+    _downloadContent = content;
     _notify = notify;
   }
   return self;
 }
 
+- (instancetype)initWithMeta:(NSString *)meta
+                         api:(NSString *)api
+                     content:(NSString *)content
+             downloadContent:(NSString *)downloadContent
+                      notify:(NSString *)notify {
+  self = [self initWithMeta:meta api:api content:content notify:notify];
+  _downloadContent = downloadContent;
+  return self;
+}
+
 - (nullable NSString *)apiV2PrefixWithRoute:(DBRoute *)route {
   switch (route.host) {
   case DBRouteHostApi:
     return [NSString stringWithFormat:@"https://%@/2", _api];
   case DBRouteHostContent:
-    return [NSString stringWithFormat:@"https://%@/2", _content];
+    if ([route.attrs[@"style"] isEqualToString:@"download"]) {
+        return [NSString stringWithFormat:@"https://%@/2", _downloadContent];
+    } else {
+        return [NSString stringWithFormat:@"https://%@/2", _content];
+    }
   case DBRouteHostNotify:
     return [NSString stringWithFormat:@"https://%@/2", _notify];
   case DBRouteHostUnknown: