Adds an IOSWebViewTypeParam() method to SearchTermsData.

ios/chrome/browser/experimental_flags.h

Index: ios/chrome/browser/experimental_flags.h
diff --git a/ios/chrome/browser/experimental_flags.h b/ios/chrome/browser/experimental_flags.h
index a284e187517c467efd35dc1efbed34a9b09c717f..0869146cb1e4f97ad2421db21b6039d4df5dc6bf 100644
--- a/ios/chrome/browser/experimental_flags.h
+++ b/ios/chrome/browser/experimental_flags.h
@@ -5,6 +5,8 @@
 #ifndef IOS_CHROME_BROWSER_EXPERIMENTAL_FLAGS_H_
 #define IOS_CHROME_BROWSER_EXPERIMENTAL_FLAGS_H_
 
+#include <string>
+
 // This file can be empty. Its purpose is to contain the relatively short lived
 // declarations required for experimental flags.
 
@@ -30,6 +32,10 @@ bool IsLRUSnapshotCacheEnabled();
 // The returned value will not change within a given session.
 bool IsWKWebViewEnabled();
 
+// Returns a string containing extra params that should be sent along with
+// omnibox search requests.  The returned value contains a leading "&".
+std::string GetWKWebViewSearchParams();
+
 // Whether keyboard commands are supported.
 bool AreKeyboardCommandsEnabled();