Enforce referrer policies for workers

Source/core/dom/ExecutionContext.cpp

Index: Source/core/dom/ExecutionContext.cpp
diff --git a/Source/core/dom/ExecutionContext.cpp b/Source/core/dom/ExecutionContext.cpp
index a559d1c459d0b23cf46a16752ff19ece544d013a..7e21b2bdb2f83d199f61ddf330202f6e21130f65 100644
--- a/Source/core/dom/ExecutionContext.cpp
+++ b/Source/core/dom/ExecutionContext.cpp
@@ -32,6 +32,7 @@
 #include "core/events/ErrorEvent.h"
 #include "core/events/EventTarget.h"
 #include "core/fetch/MemoryCache.h"
+#include "core/frame/UseCounter.h"
 #include "core/html/PublicURLManager.h"
 #include "core/inspector/InspectorInstrumentation.h"
 #include "core/inspector/ScriptCallStack.h"
@@ -73,6 +74,7 @@ ExecutionContext::ExecutionContext()
     , m_strictMixedContentCheckingEnforced(false)
     , m_windowInteractionTokens(0)
     , m_isRunSuspendableTasksScheduled(false)
+    , m_referrerPolicy(ReferrerPolicyDefault)
 {
 }
 
@@ -248,6 +250,16 @@ bool ExecutionContext::isWindowInteractionAllowed() const
     return m_windowInteractionTokens > 0;
 }
 
+void ExecutionContext::setReferrerPolicy(ReferrerPolicy referrerPolicy)
+{
+    // FIXME: Can we adopt the CSP referrer policy merge algorithm? Or does the web rely on being able to modify the referrer policy in-flight?
+    UseCounter::count(this, UseCounter::SetReferrerPolicy);
+    if (m_referrerPolicy != ReferrerPolicyDefault)
+        UseCounter::count(this, UseCounter::ResetReferrerPolicy);
+
+    m_referrerPolicy = referrerPolicy;
+}
+
 void ExecutionContext::removeURLFromMemoryCache(const KURL& url)
 {
     memoryCache()->removeURLFromCache(url);