Don't show the apps page on the NTP if the app launcher is installed.

chrome/browser/ui/webui/ntp/app_launcher_handler.cc

Index: chrome/browser/ui/webui/ntp/app_launcher_handler.cc
diff --git a/chrome/browser/ui/webui/ntp/app_launcher_handler.cc b/chrome/browser/ui/webui/ntp/app_launcher_handler.cc
index 37776021fd2801686dd4a596748d8782ea1aff32..a7082f8b77e9eaac9a4ae4c51feeab217819bc7e 100644
--- a/chrome/browser/ui/webui/ntp/app_launcher_handler.cc
+++ b/chrome/browser/ui/webui/ntp/app_launcher_handler.cc
@@ -14,6 +14,7 @@
 #include "base/metrics/histogram.h"
 #include "base/utf_string_conversions.h"
 #include "base/values.h"
+#include "chrome/browser/extensions/app_launcher.h"
 #include "chrome/browser/extensions/app_notification.h"
 #include "chrome/browser/extensions/app_notification_manager.h"
 #include "chrome/browser/extensions/crx_installer.h"
@@ -63,6 +64,29 @@ using extensions::ExtensionPrefs;
 const net::UnescapeRule::Type kUnescapeRules =
     net::UnescapeRule::NORMAL | net::UnescapeRule::URL_SPECIAL_CHARS;
 
+AppsPagePresenceHandler::AppsPagePresenceHandler() {}
+
+AppsPagePresenceHandler::~AppsPagePresenceHandler() {}
+
+void AppsPagePresenceHandler::RegisterMessages() {
+  web_ui()->RegisterMessageCallback("getShouldShowApps",
+      base::Bind(&AppsPagePresenceHandler::HandleGetShouldShowApps,
+                 base::Unretained(this)));
+}
+
+void AppsPagePresenceHandler::HandleGetShouldShowApps(const ListValue* args) {
+  extensions::GetIsAppLauncherEnabled(
+      base::Bind(&AppsPagePresenceHandler::GotIsAppLauncherEnabled,
+                 base::Unretained(this)));
+}
+
+void AppsPagePresenceHandler::GotIsAppLauncherEnabled(bool is_enabled) {
+  PrefService* prefs = Profile::FromWebUI(web_ui())->GetPrefs();
+  prefs->SetBoolean(prefs::kNtpShouldShowAppsPage, !is_enabled);
+  base::FundamentalValue should_show_apps(!is_enabled);
+  web_ui()->CallJavascriptFunction("ntp.gotShouldShowApps", should_show_apps);
+}
+
 AppLauncherHandler::AppInstallInfo::AppInstallInfo() {}
 
 AppLauncherHandler::AppInstallInfo::~AppInstallInfo() {}
@@ -779,6 +803,9 @@ void AppLauncherHandler::OnPreferenceChanged() {
 void AppLauncherHandler::RegisterUserPrefs(PrefServiceSyncable* pref_service) {
   pref_service->RegisterListPref(prefs::kNtpAppPageNames,
                                  PrefServiceSyncable::SYNCABLE_PREF);
+  pref_service->RegisterBooleanPref(prefs::kNtpShouldShowAppsPage,
+                                    true,

[Evan Stade, 2013/01/23 23:34:24]

shouldn't this default to NewTabUI::ShouldShowApps()?

[jeremya, 2013/01/24 02:40:04]

It should probably default to the result of just the synchronous checks in
extensions::GetIsAppLauncherEnabled, and NewTabUI::ShouldShowApps() should be
removed.

+                                    PrefServiceSyncable::UNSYNCABLE_PREF);
 }
 
 void AppLauncherHandler::CleanupAfterUninstall() {