Created web::UserAgentType.

ios/chrome/browser/web/chrome_web_client.mm

Index: ios/chrome/browser/web/chrome_web_client.mm
diff --git a/ios/chrome/browser/web/chrome_web_client.mm b/ios/chrome/browser/web/chrome_web_client.mm
index ccf042f332e166d5afd3775ff80fd8170d17cb16..f51bfe882deec7afe9b8ab565c60d4bb2dd1cbe1 100644
--- a/ios/chrome/browser/web/chrome_web_client.mm
+++ b/ios/chrome/browser/web/chrome_web_client.mm
@@ -108,12 +108,17 @@
   return product;
 }
 
-std::string ChromeWebClient::GetUserAgent(bool desktop_user_agent) const {
+std::string ChromeWebClient::GetUserAgent(web::UserAgentType type) const {
+  // The user agent should not be requested for app-specific URLs.
+  if (type == web::UserAgentType::NONE) {
+    NOTREACHED();
+    return std::string();

[Eugene But (OOO till 7-30), 2017/02/25 01:51:52]

DCHECK_NE(type, web::UserAgentType::NONE);

See Chromium Style Guide:
https://chromium.googlesource.com/chromium/src/+/master/styleguide/c++/c++.md...

[kkhorimoto, 2017/02/27 23:29:04]

Hmm, I had not seen those guidelines before.  I guess since there isn't any harm
in returning an inaccurate UA string here, I'll just use the DCHECK.

+  }
+
   // Using desktop user agent overrides a command-line user agent, so that
   // request desktop site can still work when using an overridden UA.
-  if (desktop_user_agent) {
+  if (type == web::UserAgentType::DESKTOP)
     return base::SysNSStringToUTF8(ChromeWebView::kDesktopUserAgent);
-  }
 
   base::CommandLine* command_line = base::CommandLine::ForCurrentProcess();
   if (command_line->HasSwitch(switches::kUserAgent)) {