Remove ability for users to launch ephemeral apps.

Test code can still do this.

BUG=517735

Review URL: https://codereview.chromium.org/1395043002

Cr-Commit-Position: refs/heads/master@{#353904}
diff --git a/chrome/browser/extensions/install_observer.cc b/chrome/browser/extensions/install_observer.cc
index 37c7565c..1145951c 100644
--- a/chrome/browser/extensions/install_observer.cc
+++ b/chrome/browser/extensions/install_observer.cc
@@ -16,7 +16,6 @@
           extension_name(extension_name),
           installing_icon(installing_icon),
           is_app(is_app),
-          is_platform_app(is_platform_app),
-          is_ephemeral(false) {}
+          is_platform_app(is_platform_app) {}
 
 }  // namespace extensions