Bug 1089417 patch 5 - Add method to save the current media query result cache key from a rule processor. r=heycam

This is needed for patch 7.

layout/style/nsCSSRuleProcessor.cpp

@@ -2925,6 +2925,17 @@ nsCSSRuleProcessor::MediumFeaturesChanged(nsPresContext* aPresContext)
   return (old != mRuleCascades);
 }
 
+UniquePtr<nsMediaQueryResultCacheKey>
+nsCSSRuleProcessor::CloneMQCacheKey()
+{
+  RuleCascadeData* c = mRuleCascades;
+  if (!c || !c->mCacheKey.HasFeatureConditions()) {
+    return nullptr;
+  }
+
+  return MakeUnique<nsMediaQueryResultCacheKey>(c->mCacheKey);
+}
+
 /* virtual */ size_t
 nsCSSRuleProcessor::SizeOfExcludingThis(MallocSizeOf aMallocSizeOf) const
 {

layout/style/nsCSSRuleProcessor.h

@@ -19,6 +19,7 @@
 #include "nsTArray.h"
 #include "nsAutoPtr.h"
 #include "nsRuleWalker.h"
+#include "mozilla/UniquePtr.h"
 
 struct CascadeEnumData;
 struct nsCSSSelector;
@@ -120,6 +121,12 @@ public:
 
   virtual bool MediumFeaturesChanged(nsPresContext* aPresContext) MOZ_OVERRIDE;
 
+  /**
+   * If this rule processor currently has a substantive media query
+   * result cache key, return a copy of it.
+   */
+  mozilla::UniquePtr<nsMediaQueryResultCacheKey> CloneMQCacheKey();
+
   virtual size_t SizeOfExcludingThis(mozilla::MallocSizeOf mallocSizeOf)
     const MOZ_MUST_OVERRIDE MOZ_OVERRIDE;
   virtual size_t SizeOfIncludingThis(mozilla::MallocSizeOf mallocSizeOf)

layout/style/nsIMediaList.h

@@ -82,6 +82,9 @@ public:
   void AddExpression(const nsMediaExpression* aExpression,
                      bool aExpressionMatches);
   bool Matches(nsPresContext* aPresContext) const;
+  bool HasFeatureConditions() const {
+    return !mFeatureCache.IsEmpty();
+  }
 
   /**
    * An operator== that implements list equality, which isn't quite as