FrameTree::Find only searches relative to local frames.

third_party/WebKit/Source/web/tests/WebFrameTest.cpp

Index: third_party/WebKit/Source/web/tests/WebFrameTest.cpp
diff --git a/third_party/WebKit/Source/web/tests/WebFrameTest.cpp b/third_party/WebKit/Source/web/tests/WebFrameTest.cpp
index 8ded215535f47e19580aa04d8161b5e21409f647..68151e4f8decad1db71e8afd5d486ac7264ea499 100644
--- a/third_party/WebKit/Source/web/tests/WebFrameTest.cpp
+++ b/third_party/WebKit/Source/web/tests/WebFrameTest.cpp
@@ -4373,8 +4373,10 @@ TEST_P(ParameterizedWebFrameTest, IframeRedirect) {
   FrameTestHelpers::PumpPendingRequestsForFrameToLoad(
       web_view_helper.WebView()->MainFrame());
 
-  WebFrame* iframe = web_view_helper.WebView()->FindFrameByName(
-      WebString::FromUTF8("ifr"), nullptr);
+  WebFrame* iframe = web_view_helper.WebView()
+                         ->MainFrame()
+                         ->ToWebLocalFrame()

[Łukasz Anforowicz, 2017/05/26 16:38:40]

ToWebLocalFrame above is okay, because otherwise the old code would have
returned null, trigerring ASSERT_TRUE(iframe) below.

[dcheng, 2017/05/26 18:28:06]

Ditto to using MainFrameImpl() here

[Łukasz Anforowicz, 2017/05/26 20:04:05]

Done (I think).

+                         ->FindFrameByName(WebString::FromUTF8("ifr"));
   ASSERT_TRUE(iframe);
   WebDataSource* iframe_data_source = iframe->DataSource();
   ASSERT_TRUE(iframe_data_source);