Fix MIME type of uploaded packages. (#14596)

When uploading, gsutil is guessing wrong about our desired MIME types. This makes it explicit.

dev/bots/prepare_package.dart

@@ -13,8 +13,7 @@ import 'package:path/path.dart' as path;
 import 'package:process/process.dart';
 import 'package:platform/platform.dart' show Platform, LocalPlatform;
 
-const String chromiumRepo =
-    'https://chromium.googlesource.com/external/github.com/flutter/flutter';
+const String chromiumRepo = 'https://chromium.googlesource.com/external/github.com/flutter/flutter';
 const String githubRepo = 'https://github.com/flutter/flutter.git';
 const String mingitForWindowsUrl = 'https://storage.googleapis.com/flutter_infra/mingit/'
     '603511c649b00bbef0a6122a827ac419b656bc19/mingit.zip';
@@ -475,8 +474,28 @@ class ArchivePublisher {
   }
 
   Future<String> _cloudCopy(String src, String dest) async {
+    // We often don't have permission to overwrite, but
+    // we have permission to remove, so that's what we do.
     await _runGsUtil(<String>['rm', dest], failOk: true);
-    return _runGsUtil(<String>['cp', src, dest]);
+    String mimeType;
+    if (dest.endsWith('.tar.xz')) {
+      mimeType = 'application/x-gtar';
+    }
+    if (dest.endsWith('.zip')) {
+      mimeType = 'application/zip';
+    }
+    if (dest.endsWith('.json')) {
+      mimeType = 'application/json';
+    }
+    final List<String> args = <String>['cp'];
+    // Use our preferred MIME type for the files we care about
+    // and let gsutil figure it out for anything else.
+    if (mimeType != null) {
+      args.addAll(<String>['-h', 'Content-Type:$mimeType']);
+    }
+    args.add(src);
+    args.add(dest);
+    return _runGsUtil(args);
   }
 }
 

dev/bots/test/prepare_package_test.dart

@@ -211,8 +211,10 @@ void main() {
 
       test('calls the right processes', () async {
         final String releasesName = 'releases_$platformName.json';
-        final String archivePath = path.join(tempDir.absolute.path, 'output_archive');
-        final String gsArchivePath = 'gs://flutter_infra/releases/dev/$platformName/output_archive';
+        final String archiveName = platform.isWindows ? 'archive.zip' : 'archive.tar.xz';
+        final String archiveMime = platform.isWindows ? 'application/zip' : 'application/x-gtar';
+        final String archivePath = path.join(tempDir.absolute.path, archiveName);
+        final String gsArchivePath = 'gs://flutter_infra/releases/dev/$platformName/$archiveName';
         final String jsonPath = path.join(tempDir.absolute.path, releasesName);
         final String gsJsonPath = 'gs://flutter_infra/releases/$releasesName';
         final String releasesJson = '''{
@@ -237,13 +239,13 @@ void main() {
 ''';
         final Map<String, List<ProcessResult>> calls = <String, List<ProcessResult>>{
           'gsutil rm $gsArchivePath': null,
-          'gsutil cp $archivePath $gsArchivePath': null,
+          'gsutil cp -h Content-Type:$archiveMime $archivePath $gsArchivePath': null,
           'gsutil cat $gsJsonPath': <ProcessResult>[new ProcessResult(0, 0, releasesJson, '')],
           'gsutil rm $gsJsonPath': null,
-          'gsutil cp $jsonPath $gsJsonPath': null,
+          'gsutil cp -h Content-Type:application/json $jsonPath $gsJsonPath': null,
         };
         processManager.fakeResults = calls;
-        final File outputFile = new File(path.join(tempDir.absolute.path, 'output_archive'));
+        final File outputFile = new File(path.join(tempDir.absolute.path, archiveName));
         assert(tempDir.existsSync());
         final ArchivePublisher publisher = new ArchivePublisher(
           tempDir,
@@ -264,7 +266,7 @@ void main() {
         // Make sure new data is added.
         expect(contents, contains('"dev": "$testRef"'));
         expect(contents, contains('"$testRef": {'));
-        expect(contents, contains('"${platformName}_archive": "dev/$platformName/output_archive"'));
+        expect(contents, contains('"${platformName}_archive": "dev/$platformName/$archiveName"'));
         // Make sure existing entries are preserved.
         expect(contents, contains('"6da8ec6bd0c4801b80d666869e4069698561c043": {'));
         expect(contents, contains('"f88c60b38c3a5ef92115d24e3da4175b4890daba": {'));