Adds a webstorePrivate method for silently installing extensions.

chrome/browser/extensions/crx_installer.cc

Index: chrome/browser/extensions/crx_installer.cc
diff --git a/chrome/browser/extensions/crx_installer.cc b/chrome/browser/extensions/crx_installer.cc
index cebc94800b4b8006415f976bde2e13cff664131d..7e151ac384077d95a1db49c952fa55f06e6d2008 100644
--- a/chrome/browser/extensions/crx_installer.cc
+++ b/chrome/browser/extensions/crx_installer.cc
@@ -56,7 +56,8 @@ static base::LazyInstance<Whitelist>
 }  // namespace
 
 CrxInstaller::WhitelistEntry::WhitelistEntry()
-  : use_app_installed_bubble(false) {}
+    : use_app_installed_bubble(false),
+      skip_post_install_ui(false) {}
 CrxInstaller::WhitelistEntry::~WhitelistEntry() {}
 
 // static
@@ -414,6 +415,8 @@ void CrxInstaller::ConfirmInstall() {
     whitelisted = true;
     if (entry->use_app_installed_bubble)
       client_->set_use_app_installed_bubble(true);
+    if (entry->skip_post_install_ui)
+      client_->set_skip_post_install_ui(true);
   }
 
   if (client_ &&