Created web::UserAgentType.

ios/web/public/user_agent.h

Index: ios/web/public/user_agent.h
diff --git a/ios/web/public/user_agent.h b/ios/web/public/user_agent.h
index 627875e8153cdfef5be06bc8037b2cf5a12956ae..55214bc0eee8d28229f558c58d7a6a42246063ad 100644
--- a/ios/web/public/user_agent.h
+++ b/ios/web/public/user_agent.h
@@ -9,6 +9,25 @@
 
 namespace web {
 
+// Enum type specifying a user agent's type.
+enum class UserAgentType : short {
+  // Used for pages that are generated for app-specific URLs.
+  NONE = 0,
+
+  // The default user agent type.  Used to specify a mobile browser user agent.

[liaoyuke, 2017/02/25 01:28:19]

Is it intentional to have multiple white spaces between "." and "Used"?

[kkhorimoto, 2017/02/25 01:35:05]

Yes.  It's a common practice to increase readability in monospaced fonts,
although not enforced by the style guide or anything.

+  MOBILE,
+
+  // Used when requesting the desktop version of a page.

[liaoyuke, 2017/02/25 01:28:19]

Can we make the comments consistent between MOBILE and DESKTOP?

Maybe change this to // Used to specify a desktop browser user agent?

[kkhorimoto, 2017/02/25 01:35:05]

Done.

+  DESKTOP
+};
+
+// Returns a string representation of |type|.
+std::string GetUserAgentTypeDescription(UserAgentType type);
+
+// Returns a UserAgentType with the given description.  If |description| doesn't
+// correspond with a UserAgentType, UserAgentType::NONE will be returned.
+UserAgentType GetUserAgentTypeWithDescription(const std::string& description);
+
 // Returns the os cpu info portion for a user agent.
 std::string BuildOSCpuInfo();