Treat unknown MIME type as application/octet-stream when launching apps.

chrome/test/data/extensions/platform_apps/launch_application_octet_stream/test.js

Index: chrome/test/data/extensions/platform_apps/launch_application_octet_stream/test.js
diff --git a/chrome/test/data/extensions/platform_apps/launch_file/test.js b/chrome/test/data/extensions/platform_apps/launch_application_octet_stream/test.js
similarity index 91%
copy from chrome/test/data/extensions/platform_apps/launch_file/test.js
copy to chrome/test/data/extensions/platform_apps/launch_application_octet_stream/test.js
index 7959573532670612579b2dac19465ed383236d28..1572c01365d808c47aed66c44cdea16c737dfeee 100644
--- a/chrome/test/data/extensions/platform_apps/launch_file/test.js
+++ b/chrome/test/data/extensions/platform_apps/launch_application_octet_stream/test.js
@@ -10,6 +10,8 @@ chrome.app.runtime.onLaunched.addListener(function (launchData) {
       chrome.test.assertEq(typeof launchData.id, 'string',
           "launchData.id not received");
       chrome.test.assertEq(launchData.items.length, 1);
+      chrome.test.assertEq(launchData.items[0].type,
+          "application/octet-stream");
 
       launchData.items[0].entry.file(function(file) {
         var reader = new FileReader();