Split Extension::ShouldDisplayInLauncher into ShouldDisplayIn{AppLauncher,NewTabPage}.

Adds manifest property show_in_new_tab_page (default value=show_in_launcher)
to give component apps a way to indicate that they should only appear in the
app launcher, and not the browser new tab page.

BUG=158880
TEST=unit_tests --gtest_filter=ExtensionTest.DisplayInXManifestProperties, and (on Windows)
settings app icon does appear on app launcher: ./chrome --user-data-dir=empty --enable-settings-app --show-app-list 
settings app icon does not appear on NTP: ./chrome --user-data-dir=empty --enable-settings-app


Review URL: https://chromiumcodereview.appspot.com/11362081

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@166849 0039d316-1c4b-4281-b951-d872f2087c98
diff --git a/chrome/browser/extensions/extension_service.cc b/chrome/browser/extensions/extension_service.cc
index ddbcf120..c1134a7 100644
--- a/chrome/browser/extensions/extension_service.cc
+++ b/chrome/browser/extensions/extension_service.cc
@@ -2088,7 +2088,7 @@
 
   // All apps that are displayed in the launcher are ordered by their ordinals
   // so we must ensure they have valid ordinals.
-  if (extension->ShouldDisplayInLauncher()) {
+  if (extension->RequiresSortOrdinal()) {
     extension_prefs_->extension_sorting()->EnsureValidOrdinals(
         extension->id(), syncer::StringOrdinal());
   }