make NavigationGesture part of public content API and use it outside content

chrome/browser/plugins/flash_download_interception_unittest.cc

Index: chrome/browser/plugins/flash_download_interception_unittest.cc
diff --git a/chrome/browser/plugins/flash_download_interception_unittest.cc b/chrome/browser/plugins/flash_download_interception_unittest.cc
index 2db60902a89e8a22d944cb1d59b372519cb01540..923b04329cc2284e4420a6f6a6bdc60e028a4620 100644
--- a/chrome/browser/plugins/flash_download_interception_unittest.cc
+++ b/chrome/browser/plugins/flash_download_interception_unittest.cc
@@ -89,7 +89,7 @@ TEST_F(FlashDownloadInterceptionTest, NavigationThrottleCancelsNavigation) {
   std::unique_ptr<NavigationHandle> handle =
       NavigationHandle::CreateNavigationHandleForTesting(
           GURL("https://get.adobe.com/flashplayer"), main_rfh(),
-          false /* committed */, net::OK, true /* has_user_gesture */);
+          false /* committed */, net::OK, content::NavigationGestureUser);
 
   handle->CallWillStartRequestForTesting(true, content::Referrer(),
                                          ui::PAGE_TRANSITION_LINK, false);