Add deprecation warnings for permission API usage from iframes

third_party/WebKit/Source/modules/encryptedmedia/NavigatorRequestMediaKeySystemAccess.cpp

Index: third_party/WebKit/Source/modules/encryptedmedia/NavigatorRequestMediaKeySystemAccess.cpp
diff --git a/third_party/WebKit/Source/modules/encryptedmedia/NavigatorRequestMediaKeySystemAccess.cpp b/third_party/WebKit/Source/modules/encryptedmedia/NavigatorRequestMediaKeySystemAccess.cpp
index 9b2f5e950b9b4e34a8d0d7d2185abc6cad37e134..e3a303da6f2f724ed2ea38c08d6be56c9f9fa778 100644
--- a/third_party/WebKit/Source/modules/encryptedmedia/NavigatorRequestMediaKeySystemAccess.cpp
+++ b/third_party/WebKit/Source/modules/encryptedmedia/NavigatorRequestMediaKeySystemAccess.cpp
@@ -327,6 +327,9 @@ ScriptPromise NavigatorRequestMediaKeySystemAccess::requestMediaKeySystemAccess(
             "The context provided is not associated with a page."));
   }
 
+  Deprecation::CountDeprecationCrossOriginIframe(

[iclelland, 2017/06/22 15:12:48]

This appears to print a deprecation message (and count usage) on every use of
requestMediaKeySystemAccess -- is that correct? Can we restrict the count to
just cases where the method was actually called in a cross-origin context, and
was blocked?

By M61, I'd like to have also distinguish between the cases where it was
implicitly blocked because no positive-policy was present, and the case where it
was explicitly blocked by a header policy, but we don't have the logic in place
for that yet.

[raymes, 2017/07/05 01:04:25]

Updated to only count if:
-Disabled by FP, and
-In cross-origin iframe

Also added a comment about the ideal behavior

+      *document, WebFeature::kEncryptedMediaDisabledIframe);
+
   // 4. Let origin be the origin of document.
   //    (Passed with the execution context.)