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

content/public/common/content_features.cc

Index: content/public/common/content_features.cc
diff --git a/content/public/common/content_features.cc b/content/public/common/content_features.cc
index 1d842a1259631a4a190152611730dd92016ba99d..f78db0afa915e7f714535296520bebf6620e8cd6 100644
--- a/content/public/common/content_features.cc
+++ b/content/public/common/content_features.cc
@@ -297,6 +297,11 @@ const base::Feature kTokenBinding{"token-binding",
 const base::Feature kTopDocumentIsolation{"top-document-isolation",
                                           base::FEATURE_DISABLED_BY_DEFAULT};
 
+// Field trial param (see base::GetFieldTrialParamValueByFeature)
+// controlling the mode for selecting which subframes end in the TDI process.
+// Valid values are integers from the TopDocumentIsolationMode enum.
+const char kTopDocumentIsolationModeParam[] = "mode";
+
 // Enables touchpad and wheel scroll latching.
 const base::Feature kTouchpadAndWheelScrollLatching{
     "TouchpadAndWheelScrollLatching", base::FEATURE_DISABLED_BY_DEFAULT};