Document usage of various URLs for loadDataWithBaseURL navs

There are a lot of URLs involved in loadDataWithBaseURL navigations, and
it's not really clear which URLs are used in various cases. This CL
tries to add more documentation around this, and adds TODOs to resolve
or investigate various potential bugs.

See doc for more details:
https://docs.google.com/document/d/1n_1uJktx-AfavP0IB-RbQ5p5jEolq2_b0VMEXnH5UQQ/edit?ts=60cd4f09#heading=h.kpvauwm3kdab

Bug: 1068965, 1223403
Change-Id: Ic52bd1baa9cfa6039f0392f9c189066649f6af49
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2971664
Commit-Queue: Rakina Zata Amni <[email protected]>
Reviewed-by: Alex Moshchuk <[email protected]>
Reviewed-by: Richard Coles <[email protected]>
Cr-Commit-Position: refs/heads/master@{#895877}
diff --git a/content/browser/renderer_host/navigation_controller_impl.cc b/content/browser/renderer_host/navigation_controller_impl.cc
index 4c22be2..4096a3b 100644
--- a/content/browser/renderer_host/navigation_controller_impl.cc
+++ b/content/browser/renderer_host/navigation_controller_impl.cc
@@ -272,15 +272,8 @@
   // URL used for the navigation.
   // TODO(https://crbug.com/1198406): Save committed origin in
   // FrameNavigationEntry for this case too.
-  absl::optional<std::string> data_url_as_string;
-#if defined(OS_ANDROID)
-  data_url_as_string = request->commit_params().data_url_as_string;
-#endif
-  if (NavigationRequest::IsLoadDataWithBaseURLAndUnreachableURL(
-          request->IsInMainFrame(), request->common_params(),
-          data_url_as_string)) {
+  if (request->IsLoadDataWithBaseURLAndHasUnreachableURL())
     return absl::nullopt;
-  }
 
   return absl::make_optional(params.origin);
 }