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 641997fc210b8c3cc52e26f4dc9cd9d98327477a..7648affc37b4a4127ddf57597489deb180da8361 100644
--- a/content/public/common/content_features.cc
+++ b/content/public/common/content_features.cc
@@ -272,6 +272,11 @@ const base::Feature kTokenBinding{"token-binding",
 const base::Feature kTopDocumentIsolation{"top-document-isolation",
                                           base::FEATURE_DISABLED_BY_DEFAULT};
 
+// Finch Experiment Param (see base::GetFieldTrialParamValueByFeature)

[Alexei Svitkine (slow), 2017/07/07 16:55:05]

In source code, we don't usually use the term "Finch". You can use Variation
param or Field trial param.

[Łukasz Anforowicz, 2017/07/07 20:41:42]

Done.

+// 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};