Fixes document type detection on iOS 9.

ios/web/web_state/ui/crw_ui_web_view_web_controller.mm

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #import "ios/web/web_state/ui/crw_ui_web_view_web_controller.h"
 
+#import "base/ios/ios_util.h"
 #import "base/ios/ns_error_util.h"
 #import "base/ios/weak_nsobject.h"
 #include "base/json/json_reader.h"
 #include "base/json/string_escape.h"
 #include "base/mac/bind_objc_block.h"
 #import "base/mac/scoped_nsobject.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/metrics/field_trial.h"
 #include "base/strings/string_util.h"
 #include "base/strings/sys_string_conversions.h"
@@ skipping 526 matching lines @@
 // The core.js cannot pass messages back to obj-c  if it is injected
 // to |WEB_VIEW_DOCUMENT| because it does not support iframe creation used
 // by core.js to communicate back. That functionality is only supported
 // by |WEB_VIEW_HTML_DOCUMENT|. |WEB_VIEW_DOCUMENT| is used when displaying
 // non-HTML contents (e.g. PDF documents).
 - (web::WebViewDocumentType)webViewDocumentType {
   // This happens during tests.
   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()) {
+    // On iOS 9, evaluating '' + document always results in [object
+    // HTMLDocument], even for PDFs. However, document.contentType is properly
+    // defined.
+    NSString* MIMEType = [_uiWebView
+        stringByEvaluatingJavaScriptFromString:@"document.contentType"];
+    return [self documentTypeFromMIMEType:MIMEType];
+  } else {
+    // On iOS 8 and below, document.contentType is always undefined. Use this
+    // instead.
+    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;
 }
 
 - (void)loadRequest:(NSMutableURLRequest*)request {
   DCHECK(web::GetWebClient());
   GURL requestURL = net::GURLWithNSURL(request.URL);
   // If the request is for WebUI, add information to let the network stack
   // access the requestGroupID.
   if (web::GetWebClient()->IsAppSpecificURL(requestURL)) {
     // Sub requests of a chrome:// page will not contain the user agent.
@@ skipping 992 matching lines @@
 }
 
 #pragma mark -
 #pragma mark Testing methods
 
 -(id<CRWRecurringTaskDelegate>)recurringTaskDelegate {
   return _recurringTaskDelegate;
 }
 
 @end