Update the error message in the Files app via Downloads panel.

chrome/browser/chromeos/file_manager/open_util.cc

Index: chrome/browser/chromeos/file_manager/open_util.cc
diff --git a/chrome/browser/chromeos/file_manager/open_util.cc b/chrome/browser/chromeos/file_manager/open_util.cc
index dbe75ccf4fd98645c7197c5b0ab98428807413b8..11be4178b6f587dcf31b9d3070946bffc1f74019 100644
--- a/chrome/browser/chromeos/file_manager/open_util.cc
+++ b/chrome/browser/chromeos/file_manager/open_util.cc
@@ -142,8 +142,14 @@ void OnContinueOpenItemCompleted(Profile* profile,
                                  const base::FilePath& file_path,
                                  bool result) {
   if (!result) {
-    ShowWarningMessageBox(
-        profile, file_path, IDS_FILE_BROWSER_ERROR_VIEWING_FILE);
+    int message;
+    if (file_path.Extension() == ".dmg")

[kinaba, 2014/09/11 08:50:41]

FILE_PATH_LITERAL(".dmg")

base::FilePath holds UTF-16 chars on Windows and UTF-8 on others.
FILE_PATH_LITERAL is a macro for absorbing the type difference.

Although the current code runs only on Chrome OS, we still want
to keep the code as portable as possible.

Same applies for ".exe" below.

[iseki, 2014/09/11 09:18:58]

Done.

+      message = IDS_FILE_BROWSER_ERROR_VIEWING_FILE_FOR_DMG;
+    else if (file_path.Extension() == ".exe")

[kinaba, 2014/09/11 08:50:41]

Would you mind checking ".msi" and returning the same message as ".exe"?
Actually I've silently tweaked it a bit for JS code last week. :)
https://codereview.chromium.org/541593003/

[iseki, 2014/09/11 09:18:58]

Done.

+      message = IDS_FILE_BROWSER_ERROR_VIEWING_FILE_FOR_EXECUTABLE;
+    else
+      message = IDS_FILE_BROWSER_ERROR_VIEWING_FILE;
+    ShowWarningMessageBox(profile, file_path, message);
   }
 }