drive: add --drive-use-shared-date to use date file was shared instead of modified date - fixes #3624

backend/drive/drive.go

@@ -326,6 +326,17 @@ Photos folder" option in your google drive settings. You can then copy
 or move the photos locally and use the date the image was taken
 (created) set as the modification date.`,
 			Advanced: true,
+		}, {
+			Name:    "use_shared_date",
+			Default: false,
+			Help: `Use date file was shared instead of modified date.
+
+Note that, as with "--drive-use-created-date", this flag may have
+unexpected consequences when uploading/downloading files.
+
+If both this flag and "--drive-use-created-date" are set, the created
+date is used.`,
+			Advanced: true,
 		}, {
 			Name:     "list_chunk",
 			Default:  1000,
@@ -463,6 +474,7 @@ type Options struct {
 	ImportExtensions          string        `config:"import_formats"`
 	AllowImportNameChange     bool          `config:"allow_import_name_change"`
 	UseCreatedDate            bool          `config:"use_created_date"`
+	UseSharedDate             bool          `config:"use_shared_date"`
 	ListChunk                 int64         `config:"list_chunk"`
 	Impersonate               string        `config:"impersonate"`
 	AlternateExport           bool          `config:"alternate_export"`
@@ -694,6 +706,9 @@ func (f *Fs) list(ctx context.Context, dirIDs []string, title string, directorie
 	if f.opt.AuthOwnerOnly {
 		fields += ",owners"
 	}
+	if f.opt.UseSharedDate {
+		fields += ",sharedWithMeTime"
+	}
 	if f.opt.SkipChecksumGphotos {
 		fields += ",spaces"
 	}
@@ -1095,6 +1110,8 @@ func (f *Fs) newBaseObject(remote string, info *drive.File) baseObject {
 	modifiedDate := info.ModifiedTime
 	if f.opt.UseCreatedDate {
 		modifiedDate = info.CreatedTime
+	} else if f.opt.UseSharedDate && info.SharedWithMeTime != "" {
+		modifiedDate = info.SharedWithMeTime
 	}
 	size := info.Size
 	if f.opt.SizeAsQuota {