arc: Implement Read and GetFileSize for ARC content file system

chrome/browser/chromeos/BUILD.gn

Index: chrome/browser/chromeos/BUILD.gn
diff --git a/chrome/browser/chromeos/BUILD.gn b/chrome/browser/chromeos/BUILD.gn
index 1b494e37dbf5950579769483308d1d9a6fb988df..66166162b24e103d1f89c6401dd7bf4eea553e2e 100644
--- a/chrome/browser/chromeos/BUILD.gn
+++ b/chrome/browser/chromeos/BUILD.gn
@@ -226,6 +226,8 @@ source_set("chromeos") {
     "arc/fileapi/arc_content_file_system_service.h",
     "arc/fileapi/arc_content_file_system_url_util.cc",
     "arc/fileapi/arc_content_file_system_url_util.h",
+    "arc/fileapi/intent_helper_util.cc",
+    "arc/fileapi/intent_helper_util.h",
     "arc/intent_helper/arc_external_protocol_dialog.cc",
     "arc/intent_helper/arc_external_protocol_dialog.h",
     "arc/intent_helper/arc_navigation_throttle.cc",
@@ -1371,6 +1373,8 @@ source_set("unit_tests") {
     "accessibility/spoken_feedback_event_rewriter_unittest.cc",
     "arc/arc_auth_service_unittest.cc",
     "arc/downloads_watcher/arc_downloads_watcher_service_unittest.cc",
+    "arc/fileapi/arc_content_file_system_async_file_util_unittest.cc",
+    "arc/fileapi/arc_content_file_system_file_stream_reader_unittest.cc",
     "arc/fileapi/arc_content_file_system_url_util_unittest.cc",
     "arc/intent_helper/arc_external_protocol_dialog_unittest.cc",
     "arc/intent_helper/arc_navigation_throttle_unittest.cc",