Switch to UTTypeCopyAllTagsWithClass.

This allows us to remove the use of a private API.

Bug: 1027401
Change-Id: I1cd0e236fdb4ded2093a4120a0af326b57d9efd5
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1929848
Auto-Submit: Avi Drissman <avi@chromium.org>
Commit-Queue: Matt Mueller <mattm@chromium.org>
Reviewed-by: Sidney San Martín <sdy@chromium.org>
Reviewed-by: Matt Mueller <mattm@chromium.org>
Cr-Commit-Position: refs/heads/master@{#718877}

net/base/platform_mime_util_mac.mm

@@ -18,16 +18,6 @@
 #include <CoreServices/CoreServices.h>
 #endif  // defined(OS_IOS)
 
-#if !defined(OS_IOS)
-// SPI declaration; see the commentary in GetPlatformExtensionsForMimeType.
-// iOS must not use any private API, per Apple guideline.
-
-@interface NSURLFileTypeMappings : NSObject
-+ (NSURLFileTypeMappings*)sharedMappings;
-- (NSArray*)extensionsForMIMEType:(NSString*)mimeType;
-@end
-#endif  // !defined(OS_IOS)
-
 namespace net {
 
 bool PlatformMimeUtil::GetPlatformMimeTypeFromExtension(
@@ -40,7 +30,7 @@ bool PlatformMimeUtil::GetPlatformMimeTypeFromExtension(
   if (!ext_ref)
     return false;
   base::ScopedCFTypeRef<CFStringRef> uti(UTTypeCreatePreferredIdentifierForTag(
-      kUTTagClassFilenameExtension, ext_ref, NULL));
+      kUTTagClassFilenameExtension, ext_ref, nullptr));
   if (!uti)
     return false;
   base::ScopedCFTypeRef<CFStringRef> mime_ref(
@@ -60,7 +50,7 @@ bool PlatformMimeUtil::GetPlatformPreferredExtensionForMimeType(
   if (!mime_ref)
     return false;
   base::ScopedCFTypeRef<CFStringRef> uti(UTTypeCreatePreferredIdentifierForTag(
-      kUTTagClassMIMEType, mime_ref, NULL));
+      kUTTagClassMIMEType, mime_ref, nullptr));
   if (!uti)
     return false;
   base::ScopedCFTypeRef<CFStringRef> ext_ref(
@@ -75,22 +65,21 @@ bool PlatformMimeUtil::GetPlatformPreferredExtensionForMimeType(
 void PlatformMimeUtil::GetPlatformExtensionsForMimeType(
     const std::string& mime_type,
     std::unordered_set<base::FilePath::StringType>* extensions) const {
-#if defined(OS_IOS)
-  NSArray* extensions_list = nil;
-#else
-  // There is no API for this that uses UTIs. The WebKitSystemInterface call
-  // WKGetExtensionsForMIMEType() is a thin wrapper around
-  // [[NSURLFileTypeMappings sharedMappings] extensionsForMIMEType:], which is
-  // used by Firefox as well.
-  //
-  // See:
-  // http://mxr.mozilla.org/mozilla-central/search?string=extensionsForMIMEType
-  // http://www.openradar.me/11384153
-  // rdar://11384153
-  NSArray* extensions_list =
-      [[NSURLFileTypeMappings sharedMappings]
-          extensionsForMIMEType:base::SysUTF8ToNSString(mime_type)];
-#endif  // defined(OS_IOS)
+  base::ScopedCFTypeRef<CFArrayRef> exts_ref;
+
+  base::ScopedCFTypeRef<CFStringRef> mime_ref(
+      base::SysUTF8ToCFStringRef(mime_type));
+  if (mime_ref) {
+    base::ScopedCFTypeRef<CFStringRef> uti(
+        UTTypeCreatePreferredIdentifierForTag(kUTTagClassMIMEType, mime_ref,
+                                              nullptr));
+    if (uti) {
+      exts_ref.reset(
+          UTTypeCopyAllTagsWithClass(uti, kUTTagClassFilenameExtension));
+    }
+  }
+
+  NSArray* extensions_list = base::mac::CFToNSCast(exts_ref);
 
   if (extensions_list) {
     for (NSString* extension in extensions_list)