Add metrics for usage of permission features from iframes in blink

third_party/WebKit/Source/core/frame/UseCounter.cpp

Index: third_party/WebKit/Source/core/frame/UseCounter.cpp
diff --git a/third_party/WebKit/Source/core/frame/UseCounter.cpp b/third_party/WebKit/Source/core/frame/UseCounter.cpp
index 640c8109986dde4ea7497ccc85ea1b63d27d5403..2682816baf63ab48c5c8966ac3c4408cbf2f795b 100644
--- a/third_party/WebKit/Source/core/frame/UseCounter.cpp
+++ b/third_party/WebKit/Source/core/frame/UseCounter.cpp
@@ -730,6 +730,17 @@ void UseCounter::countDeprecationIfNotPrivateScript(v8::Isolate* isolate, Execut
     UseCounter::countDeprecation(context, feature);
 }
 
+void UseCounter::countCrossOriginIframe(const Document& document, Feature feature)
+{
+    Frame* frame = document.frame();
+    if (!frame)
+        return;
+    SecurityOrigin* securityOrigin = frame->securityContext()->securityOrigin();
+    Frame* parent = frame->tree().parent();
+    if (parent && !securityOrigin->canAccess(parent->securityContext()->securityOrigin()))

[mlamouri (slow - plz ping), 2016/01/19 17:54:48]

canAccess() is not exactly "cross origin". Maybe this should be specified in the
header.

[raymes, 2016/01/20 00:13:12]

Done. Actually you made me realise that this code isn't good enough. We want to
check if the frame has access into the top level document. It may be able to
script into its parent but the parent may be a different origin to the top level
document.

+        count(frame, feature);
+}
+
 static const char* milestoneString(int milestone)
 {
     switch (milestone) {