Rename GetMainFrame to GetPrimaryMainFrame

Progressively rename some usages of GetMainFrame to GetPrimaryMainFrame.

This is an automated change via emacs xref integration via codesearch.

BUG=1250404

Change-Id: Ibb5ca2055776693b332e26d7b348b81d65d1900c
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3692390
Owners-Override: Nasko Oskov <[email protected]>
Commit-Queue: Dave Tapuska <[email protected]>
Reviewed-by: Nasko Oskov <[email protected]>
Cr-Commit-Position: refs/heads/main@{#1011655}
diff --git a/components/custom_handlers/protocol_handler_registry_browsertest.cc b/components/custom_handlers/protocol_handler_registry_browsertest.cc
index 5d3a0025..1a92438b 100644
--- a/components/custom_handlers/protocol_handler_registry_browsertest.cc
+++ b/components/custom_handlers/protocol_handler_registry_browsertest.cc
@@ -157,7 +157,7 @@
   // Create a FencedFrame.
   content::RenderFrameHost* fenced_frame_host =
       fenced_frame_test_helper().CreateFencedFrame(
-          web_contents()->GetMainFrame(),
+          web_contents()->GetPrimaryMainFrame(),
           embedded_test_server()->GetURL("/fenced_frames/title1.html"));
   ASSERT_TRUE(fenced_frame_host);