Add nsIDOMWindowUtils::getVisitedDependentComputedStyle for use in tests. (Bug 147777) r=bzbarsky

dom/base/nsDOMWindowUtils.cpp

@@ -66,6 +66,7 @@
 #include "gfxContext.h"
 #include "gfxImageSurface.h"
 #include "nsLayoutUtils.h"
+#include "nsComputedDOMStyle.h"
 
 #if defined(MOZ_X11) && defined(MOZ_WIDGET_GTK2)
 #include <gdk/gdk.h>
@@ -1224,3 +1225,26 @@ nsDOMWindowUtils::GetClassName(char **aName)
   *aName = NS_strdup(JS_GET_CLASS(cx, JSVAL_TO_OBJECT(argv[0]))->name);
   return *aName ? NS_OK : NS_ERROR_OUT_OF_MEMORY;
 }
+
+NS_IMETHODIMP
+nsDOMWindowUtils::GetVisitedDependentComputedStyle(
+                    nsIDOMElement *aElement, const nsAString& aPseudoElement,
+                    const nsAString& aPropertyName, nsAString& aResult)
+{
+  aResult.Truncate();
+
+  if (!IsUniversalXPConnectCapable()) {
+    return NS_ERROR_DOM_SECURITY_ERR;
+  }
+
+  nsCOMPtr<nsIDOMCSSStyleDeclaration> decl;
+  nsresult rv =
+    mWindow->GetComputedStyle(aElement, aPseudoElement, getter_AddRefs(decl));
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  static_cast<nsComputedDOMStyle*>(decl.get())->SetExposeVisitedStyle(PR_TRUE);
+  rv = decl->GetPropertyValue(aPropertyName, aResult);
+  static_cast<nsComputedDOMStyle*>(decl.get())->SetExposeVisitedStyle(PR_FALSE);
+
+  return rv;
+}

dom/interfaces/base/nsIDOMWindowUtils.idl

@@ -52,7 +52,7 @@ interface nsIDOMEvent;
 interface nsITransferable;
 interface nsIQueryContentEventResult;
 
-[scriptable, uuid(00ca8d4f-61f1-4d9c-a7c1-82651b0cf02b)]
+[scriptable, uuid(1e9d7efa-997d-42c0-acdf-f5f1cc8eb539)]
 interface nsIDOMWindowUtils : nsISupports {
 
   /**
@@ -613,4 +613,22 @@ interface nsIDOMWindowUtils : nsISupports {
   boolean sendSelectionSetEvent(in unsigned long aOffset,
                                 in unsigned long aLength,
                                 in boolean aReverse);
+
+  /**
+   * Perform the equivalent of:
+   *   window.getComputedStyle(aElement, aPseudoElement).
+   *     getPropertyValue(aPropertyName)
+   * except that, when the link whose presence in history is allowed to
+   * influence aElement's style is visited, get the value the property
+   * would have if allowed all properties to change as a result of
+   * :visited selectors (except for cases where getComputedStyle uses
+   * data from the frame).
+   *
+   * This is easier to implement than adding our property restrictions
+   * to this API, and is sufficient for the present testing
+   * requirements (which are essentially testing 'color').
+   */
+  AString getVisitedDependentComputedStyle(in nsIDOMElement aElement,
+                                           in AString aPseudoElement,
+                                           in AString aPropertyName);
 };

layout/style/nsComputedDOMStyle.cpp

@@ -132,7 +132,8 @@ GetContainingBlockFor(nsIFrame* aFrame) {
 
 nsComputedDOMStyle::nsComputedDOMStyle()
   : mDocumentWeak(nsnull), mOuterFrame(nsnull),
-    mInnerFrame(nsnull), mPresShell(nsnull), mAppUnitsPerInch(0)
+    mInnerFrame(nsnull), mPresShell(nsnull), mAppUnitsPerInch(0),
+    mExposeVisitedStyle(PR_FALSE)
 {
 }
 
@@ -500,6 +501,19 @@ nsComputedDOMStyle::GetPropertyCSSValue(const nsAString& aPropertyName,
                  "should not have pseudo-element data");
   }
 
+  // mExposeVisitedStyle is set to true only by testing APIs that
+  // require UniversalXPConnect.
+  NS_ABORT_IF_FALSE(!mExposeVisitedStyle ||
+                    nsContentUtils::IsCallerTrustedForCapability(
+                                      "UniversalXPConnect"),
+                    "mExposeVisitedStyle set incorrectly");
+  if (mExposeVisitedStyle && mStyleContextHolder->RelevantLinkVisited()) {
+    nsStyleContext *styleIfVisited = mStyleContextHolder->GetStyleIfVisited();
+    if (styleIfVisited) {
+      mStyleContextHolder = styleIfVisited;
+    }
+  }
+
   // Call our pointer-to-member-function.
   nsresult rv = (this->*(propEntry->mGetter))(aReturn);
 

layout/style/nsComputedDOMStyle.h

@@ -92,6 +92,12 @@ public:
   static nsIPresShell*
   GetPresShellForContent(nsIContent* aContent);
 
+  // Helper for nsDOMWindowUtils::GetVisitedDependentComputedStyle
+  void SetExposeVisitedStyle(PRBool aExpose) {
+    NS_ASSERTION(aExpose != mExposeVisitedStyle, "should always be changing");
+    mExposeVisitedStyle = aExpose;
+  }
+
 private:
   void AssertFlushedPendingReflows() {
     NS_ASSERTION(mFlushedPendingReflows,
@@ -472,6 +478,8 @@ private:
 
   PRInt32 mAppUnitsPerInch; /* For unit conversions */
 
+  PRPackedBool mExposeVisitedStyle;
+
 #ifdef DEBUG
   PRBool mFlushedPendingReflows;
 #endif