arc: Use the MIME type returned by the container to handle content URLs

chrome/browser/chromeos/arc/fileapi/arc_content_file_system_async_file_util_unittest.cc

Index: chrome/browser/chromeos/arc/fileapi/arc_content_file_system_async_file_util_unittest.cc
diff --git a/chrome/browser/chromeos/arc/fileapi/arc_content_file_system_async_file_util_unittest.cc b/chrome/browser/chromeos/arc/fileapi/arc_content_file_system_async_file_util_unittest.cc
index 4e5834d56322ab226477c740365e25ddade48606..73425246908e4edc9f95e34c8dae6a266918ee53 100644
--- a/chrome/browser/chromeos/arc/fileapi/arc_content_file_system_async_file_util_unittest.cc
+++ b/chrome/browser/chromeos/arc/fileapi/arc_content_file_system_async_file_util_unittest.cc
@@ -31,6 +31,7 @@ namespace {
 
 constexpr char kArcUrl[] = "content://org.chromium.foo/bar";
 constexpr char kData[] = "abcdef";
+constexpr char kMimeType[] = "application/octet-stream";
 
 class ArcContentFileSystemAsyncFileUtilTest : public testing::Test {
  public:
@@ -38,7 +39,8 @@ class ArcContentFileSystemAsyncFileUtilTest : public testing::Test {
   ~ArcContentFileSystemAsyncFileUtilTest() override = default;
 
   void SetUp() override {
-    fake_file_system_.AddFile(File(kArcUrl, kData, File::Seekable::NO));
+    fake_file_system_.AddFile(
+        File(kArcUrl, kData, kMimeType, File::Seekable::NO));
 
     arc_service_manager_ = base::MakeUnique<ArcServiceManager>(nullptr);
     arc_service_manager_->AddService(