(re-commit) Implement installation of the Chrome App Host.

chrome/common/chrome_switches.cc

Index: chrome/common/chrome_switches.cc
diff --git a/chrome/common/chrome_switches.cc b/chrome/common/chrome_switches.cc
index f7ab36416b527bacf999cbafd46a3fa0eeaed671..9e5e06b9446ba018a467040a9d5069a4ffb95bc4 100644
--- a/chrome/common/chrome_switches.cc
+++ b/chrome/common/chrome_switches.cc
@@ -91,6 +91,10 @@ const char kAppsGalleryURL[]                = "apps-gallery-url";
 // The update url used by gallery/webstore extensions.
 const char kAppsGalleryUpdateURL[]          = "apps-gallery-update-url";
 
+// Specifies the URL of an application manifest to retrieve. The user will be
+// prompted for consent and the application retrieved/installed if consented.
+const char kAppsInstallFromManifestURL[]    = "apps-install-from-manifest-url";
+
 // Whether to always use the new app install bubble when installing an app.
 const char kAppsNewInstallBubble[]          = "apps-new-install-bubble";