Add UMA for header values in XHR's setRequestHeader() checked against RFC 7230

third_party/WebKit/Source/core/xmlhttprequest/XMLHttpRequest.cpp

Index: third_party/WebKit/Source/core/xmlhttprequest/XMLHttpRequest.cpp
diff --git a/third_party/WebKit/Source/core/xmlhttprequest/XMLHttpRequest.cpp b/third_party/WebKit/Source/core/xmlhttprequest/XMLHttpRequest.cpp
index 7e5e8ef292b0cdce0a6fcd28d3c14b48ba903465..a996e3919cb1830b7f5d7710bafaa55fcf2f62b0 100644
--- a/third_party/WebKit/Source/core/xmlhttprequest/XMLHttpRequest.cpp
+++ b/third_party/WebKit/Source/core/xmlhttprequest/XMLHttpRequest.cpp
@@ -1174,10 +1174,6 @@ void XMLHttpRequest::setRequestHeader(const AtomicString& name, const AtomicStri
         return;
     }
 
-    // Show deprecation warnings and count occurrences of such deprecated header values.
-    if (!value.isEmpty() && !isValidHTTPFieldContentRFC7230(value))
-        UseCounter::countDeprecation(executionContext(), UseCounter::HeaderValueNotMatchingRFC7230);
-
     // No script (privileged or not) can set unsafe headers.
     if (FetchUtils::isForbiddenHeaderName(name)) {
         logConsoleError(executionContext(), "Refused to set unsafe header \"" + name + "\"");
@@ -1189,9 +1185,32 @@ void XMLHttpRequest::setRequestHeader(const AtomicString& name, const AtomicStri
 
 void XMLHttpRequest::setRequestHeaderInternal(const AtomicString& name, const AtomicString& value)
 {
+    // We show deprecation warnings if |value| is still invalid header value
+    // after normalization (i.e. contains invalid octets).
+    String normalizedValue = FetchUtils::normalizeHeaderValue(value);
+    if (!normalizedValue.isEmpty() && !isValidHTTPFieldContentRFC7230(normalizedValue))
+        UseCounter::countDeprecation(executionContext(), UseCounter::HeaderValueNotMatchingRFC7230);
+
     HTTPHeaderMap::AddResult result = m_requestHeaders.add(name, value);
-    if (!result.isNewEntry)
-        result.storedValue->value = result.storedValue->value + ", " + value;
+    if (result.isNewEntry)
+        return;
+
+    AtomicString newValue = result.storedValue->value + ", " + value;
+
+    // We show deprecation warnings if this call to setRequestHeader() is
+    // affected by header value normalization.
+    // Without normalization at XHR level here, the actual header value
+    // sent to the network is |newValue| with leading/trailing whitespaces
+    // stripped (i.e. |normalizeHeaderValue(newValue)|).
+    // With normalization at XHR level here as the spec requires, the
+    // actual header value sent to the network is |normalizedNewValue|.
+    // If these two are different, introducing normalization here affects
+    // the header value sent to the network so we show warnings.
+    String normalizedNewValue = FetchUtils::normalizeHeaderValue(result.storedValue->value) + ", " + FetchUtils::normalizeHeaderValue(value);
+    if (FetchUtils::normalizeHeaderValue(newValue) != normalizedNewValue)
+        UseCounter::countDeprecation(executionContext(), UseCounter::XHRSetRequestHeaderAffectedByNormalization);
+
+    result.storedValue->value = newValue;
 }
 
 const AtomicString& XMLHttpRequest::getRequestHeader(const AtomicString& name) const