Bug 1543068 - P1.5 Remove InheritedEmbedderPolicy r=nika

I believe it's the right thing to do.
COEP inherits opener's COEP and is overwritten if COEP by response is stricter.
i.e., we no more need the inherited one.

Differential Revision: https://phabricator.services.mozilla.com/D40143

docshell/base/BrowsingContext.cpp

@@ -134,12 +134,12 @@ already_AddRefed<BrowsingContext> BrowsingContext::Create(
   context->mName = aName;
   context->mOpenerId = aOpener ? aOpener->Id() : 0;
   context->mEmbedderPolicy = nsILoadInfo::EMBEDDER_POLICY_NULL;
-  context->mInheritedEmbedderPolicy = nsILoadInfo::EMBEDDER_POLICY_NULL;
 
   BrowsingContext* inherit = aParent ? aParent : aOpener;
   if (inherit) {
     context->mOpenerPolicy = inherit->mOpenerPolicy;
-    context->mInheritedEmbedderPolicy = inherit->mEmbedderPolicy;
+    // CORPP 3.1.3 https://mikewest.github.io/corpp/#integration-html
+    context->mEmbedderPolicy = inherit->mEmbedderPolicy;
   }
 
   Register(context);

docshell/base/BrowsingContextFieldList.h

@@ -13,7 +13,6 @@
 MOZ_BC_FIELD(Name, nsString)
 MOZ_BC_FIELD(Closed, bool)
 MOZ_BC_FIELD(EmbedderPolicy, nsILoadInfo::CrossOriginEmbedderPolicy)
-MOZ_BC_FIELD(InheritedEmbedderPolicy, nsILoadInfo::CrossOriginEmbedderPolicy)
 MOZ_BC_FIELD(OpenerPolicy, nsILoadInfo::CrossOriginOpenerPolicy)
 
 // The current opener for this BrowsingContext. This is a weak reference, and

netwerk/protocol/http/nsHttpChannel.cpp

@@ -7528,21 +7528,21 @@ nsresult nsHttpChannel::ProcessCrossOriginEmbedderPolicyHeader() {
   }
 
   nsILoadInfo::CrossOriginEmbedderPolicy documentPolicy =
-      ctx->GetInheritedEmbedderPolicy();
+      ctx->GetEmbedderPolicy();
   nsILoadInfo::CrossOriginEmbedderPolicy resultPolicy =
       nsILoadInfo::EMBEDDER_POLICY_NULL;
   rv = GetResponseEmbedderPolicy(&resultPolicy);
   if (NS_FAILED(rv)) {
     return NS_OK;
   }
 
-  ctx->SetEmbedderPolicy(resultPolicy);
-
   if (documentPolicy != nsILoadInfo::EMBEDDER_POLICY_NULL &&
       resultPolicy == nsILoadInfo::EMBEDDER_POLICY_NULL) {
     return NS_ERROR_BLOCKED_BY_POLICY;
   }
 
+  ctx->SetEmbedderPolicy(resultPolicy);
+
   return NS_OK;
 }