Fixes document type detection on iOS 9.

ios/web/web_state/ui/crw_ui_web_view_web_controller.mm

Index: ios/web/web_state/ui/crw_ui_web_view_web_controller.mm
diff --git a/ios/web/web_state/ui/crw_ui_web_view_web_controller.mm b/ios/web/web_state/ui/crw_ui_web_view_web_controller.mm
index 5efb858d0e6f8282bb24ef10662775e5e9ee5150..a232ad3d0d0e3c3d9372fadb8692916c8b960c79 100644
--- a/ios/web/web_state/ui/crw_ui_web_view_web_controller.mm
+++ b/ios/web/web_state/ui/crw_ui_web_view_web_controller.mm
@@ -550,13 +550,23 @@ const size_t kMaxMessageQueueSize = 262144;
   if (!_uiWebView) {
     return web::WEB_VIEW_DOCUMENT_TYPE_GENERIC;
   }
-  NSString* documentType =
-      [_uiWebView stringByEvaluatingJavaScriptFromString:
-          @"'' + document"];
-  if ([documentType isEqualToString:@"[object HTMLDocument]"])
-    return web::WEB_VIEW_DOCUMENT_TYPE_HTML;
-  else if ([documentType isEqualToString:@"[object Document]"])
-    return web::WEB_VIEW_DOCUMENT_TYPE_GENERIC;
+
+  if (base::ios::IsRunningOnIOS9OrLater()) {

[Eugene But (OOO till 7-30), 2015/11/18 16:30:57]

Please explain in the comments why iOS9 implementation is different.

[stkhapugin, 2015/11/19 16:16:35]

Done.

+    NSString* documentType = [_uiWebView
+        stringByEvaluatingJavaScriptFromString:@"document.contentType"];
+    if ([documentType isEqualToString:@"text/html"])

[Eugene But (OOO till 7-30), 2015/11/18 16:30:57]

I think you also want to check for "application/xhtml+xml" and "application/xml"
MIME types. And please unify this code with -[CRWWKWebViewWebController
webViewDocumentType] by adding |documentTypeFromMIMEType:| method to
CRWWebController.

[stkhapugin, 2015/11/19 16:16:35]

Done.

+      return web::WEB_VIEW_DOCUMENT_TYPE_HTML;
+    else if ([documentType isEqualToString:@"application/pdf"])
+      return web::WEB_VIEW_DOCUMENT_TYPE_GENERIC;
+  } else {
+    NSString* documentType =
+        [_uiWebView stringByEvaluatingJavaScriptFromString:@"'' + document"];
+    if ([documentType isEqualToString:@"[object HTMLDocument]"])
+      return web::WEB_VIEW_DOCUMENT_TYPE_HTML;
+    else if ([documentType isEqualToString:@"[object Document]"])
+      return web::WEB_VIEW_DOCUMENT_TYPE_GENERIC;
+  }
+
   return web::WEB_VIEW_DOCUMENT_TYPE_UNKNOWN;
 }