[iOS] Upstream switches and flags controlling which WebView is used

ios/chrome/browser/chrome_switches.cc

Index: ios/chrome/browser/chrome_switches.cc
diff --git a/ios/chrome/browser/chrome_switches.cc b/ios/chrome/browser/chrome_switches.cc
index 89d3637ae29eff4c0913c68c431c13ff9af8eba0..76afaefed6f476a7ca763a4677fd82dd6820a0cc 100644
--- a/ios/chrome/browser/chrome_switches.cc
+++ b/ios/chrome/browser/chrome_switches.cc
@@ -12,9 +12,15 @@ namespace switches {
 // all work out.
 // -----------------------------------------------------------------------------
 
+// Disables the use of WKWebView instead of UIWebView.
+const char kDisableIOSWKWebView[] = "disable-wkwebview";
+
 // Enables Open from Clipboard.
 const char kEnableIOSOpenFromClipboard[] = "enable-ios-open-from-clipboard";
 
+// Enables the use of WKWebView instead of UIWebView.
+const char kEnableIOSWKWebView[] = "enable-wkwebview";
+
 // Defines the value in MB of the memory wedge to insert at cold launch.
 const char kIOSMemoryWedgeSize[] = "ios-memory-wedge-size-mb";