Experimental Feature: Allow-CSP-From header

third_party/WebKit/Source/core/frame/csp/ContentSecurityPolicy.cpp

Index: third_party/WebKit/Source/core/frame/csp/ContentSecurityPolicy.cpp
diff --git a/third_party/WebKit/Source/core/frame/csp/ContentSecurityPolicy.cpp b/third_party/WebKit/Source/core/frame/csp/ContentSecurityPolicy.cpp
index 20fd403634bfeb45b58118b95618255ee188787f..0c211301541184f4d3f3dada2f670ecea189936d 100644
--- a/third_party/WebKit/Source/core/frame/csp/ContentSecurityPolicy.cpp
+++ b/third_party/WebKit/Source/core/frame/csp/ContentSecurityPolicy.cpp
@@ -311,6 +311,31 @@ void ContentSecurityPolicy::didReceiveHeader(
     applyPolicySideEffectsToExecutionContext();
 }
 
+bool ContentSecurityPolicy::shouldEnforceEmbeddersPolicy(

[Mike West, 2016/10/14 09:01:17]

Can you add some unit tests for this method in `ContentSecurityPolicyTest.cpp`?

+    const ResourceResponse& response,
+    SecurityOrigin* parentOrigin) {
+  if (response.url().isEmpty() || response.url().protocolIsAbout() ||
+      response.url().protocolIsData() || response.url().protocolIs("blob") ||
+      response.url().protocolIs("filesystem")) {
+    return true;
+  }
+
+  if (parentOrigin->canAccess(SecurityOrigin::create(response.url()).get()))
+    return true;
+
+  String header = response.httpHeaderField(HTTPNames::Allow_CSP_From);
+  if (header.isEmpty() || !header.containsOnlyASCII())
+    return false;
+
+  String headerValue = header.stripWhiteSpace();
+  if (headerValue == "*" ||
+      parentOrigin->canAccess(
+          SecurityOrigin::createFromString(headerValue).get()))

[Mike West, 2016/10/14 09:01:17]

I think you can simplify the logic here a bit with something like:

```
String header = response.httpHeaderField(HTTPNames::Allow_CSP_From);
header = header.stripWhiteSpace();
if (header == "*")
  return true;
if (RefPtr<SecurityOrigin> childOrigin =
SecurityOrigin::createFromString(header))
  return parentOrigin->canAccess(childOrigin);

return false;
```

+    return true;

[Mike West, 2016/10/14 09:01:17]

Nit: `{}` around the body if the `if` clause is multi-line.

+
+  return false;
+}
+
 void ContentSecurityPolicy::addPolicyFromHeaderValue(
     const String& header,
     ContentSecurityPolicyHeaderType type,