Use FrameIsAd to decide whether to isolate a frame in TopDocumentIsolation mode.

content/public/browser/content_browser_client.h

Index: content/public/browser/content_browser_client.h
diff --git a/content/public/browser/content_browser_client.h b/content/public/browser/content_browser_client.h
index 41cd656e552d09afa091b32e43211fe06d77b8e2..be177952b9f2baf9aaa88150bb941c294c824d13 100644
--- a/content/public/browser/content_browser_client.h
+++ b/content/public/browser/content_browser_client.h
@@ -9,6 +9,7 @@
 
 #include <map>
 #include <memory>
+#include <set>
 #include <string>
 #include <utility>
 #include <vector>
@@ -261,13 +262,16 @@ class CONTENT_EXPORT ContentBrowserClient {
                                         bool* is_renderer_initiated,
                                         content::Referrer* referrer) {}
 
-  // Allows the embedder to override top document isolation for specific frames.
-  // |url| is the URL being loaded in the subframe, and |parent_site_instance|
-  // is the SiteInstance of the parent frame. Called only for subframes and only
-  // when top document isolation mode is enabled.
-  virtual bool ShouldFrameShareParentSiteInstanceDespiteTopDocumentIsolation(
-      const GURL& url,
-      SiteInstance* parent_site_instance);
+  // Called in TopDocumentIsolation mode to let the embedder decide whether the
+  // subframe navigation tracked by |navigation_handle| should end up isolated
+  // from the main content.
+  //
+  // The subframe navigation in question is always to a URL that is cross-site
+  // from the top-level frame.  |main_frame_site_instance| is the SiteInstance
+  // of the top-level frame.
+  virtual bool ShouldIsolateFrameForTopDocumentIsolation(
+      NavigationHandle* navigation_handle,
+      SiteInstance* main_frame_site_instance);
 
   // Returns whether a new view for a given |site_url| can be launched in a
   // given |process_host|.