Fix crash when referencing a registered non-inherited custom property

This patch fixes a crash that occurs when a registered non-inherited custom property is referenced on an element which doesn't explicitly have any registered non-inherited custom properties set. The code was missing a null-check for the non-inherited custom properties object. Note that elsewhere in the file this is not needed as the object is guaranteed to exist when we are resolving such properties. BUG=671484 Review-Url: https://codereview.chromium.org/2552163002 Cr-Commit-Position: refs/heads/master@{#436880}
hylschwy · Dec 7, 2016 · 1bf1f4c · 1bf1f4c
1 parent a24451f
commit 1bf1f4c
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diff --git a/third_party/WebKit/LayoutTests/custom-properties/registered-property-initial.html b/third_party/WebKit/LayoutTests/custom-properties/registered-property-initial.html
@@ -0,0 +1,23 @@
+<!DOCTYPE HTML>
+<script src="../resources/testharness.js"></script>
+<script src="../resources/testharnessreport.js"></script>
+<style>
+#target {
+  background: var(--inherited-color);
+  color: var(--non-inherited-color);
+}
+</style>
+<div id=target></div>
+<script>
+CSS.registerProperty({name: '--inherited-color', syntax: '<color>', initialValue: 'pink', inherits: true});
+CSS.registerProperty({name: '--non-inherited-color', syntax: '<color>', initialValue: 'purple'});
+
+test(function() {
+    computedStyle = getComputedStyle(target);
+    assert_equals(computedStyle.getPropertyValue('--inherited-color'), 'pink');
+    assert_equals(computedStyle.getPropertyValue('--non-inherited-color'), 'purple');
+
+    assert_equals(computedStyle.backgroundColor, 'rgb(255, 192, 203)');
+    assert_equals(computedStyle.color, 'rgb(128, 0, 128)');
+}, "Initial values of registered properties can be referenced when no custom properties are explicitly set.");
+</script>
diff --git a/third_party/WebKit/Source/core/css/resolver/CSSVariableResolver.cpp b/third_party/WebKit/Source/core/css/resolver/CSSVariableResolver.cpp
@@ -53,7 +53,8 @@ CSSVariableData* CSSVariableResolver::valueForCustomProperty(
     if (m_inheritedVariables)
       variableData = m_inheritedVariables->getVariable(name);
   } else {
-    variableData = m_nonInheritedVariables->getVariable(name);
+    if (m_nonInheritedVariables)
+      variableData = m_nonInheritedVariables->getVariable(name);
   }
   if (!variableData)
     return registration ? registration->initialVariableData() : nullptr;