Bug 1089417 patch 4 - Define equality operators on nsMediaQueryResultCacheKey and the types it contains. r=heycam

This is needed for the equality comparison in
nsCSSRuleProcessor::MediumFeaturesChanged in patch 8.

layout/style/nsIMediaList.h

@@ -37,7 +37,16 @@ struct nsMediaExpression {
 
   // aActualValue must be obtained from mFeature->mGetter
   bool Matches(nsPresContext* aPresContext,
-                 const nsCSSValue& aActualValue) const;
+               const nsCSSValue& aActualValue) const;
+
+  bool operator==(const nsMediaExpression& aOther) const {
+    return mFeature == aOther.mFeature && // pointer equality fine (atom-like)
+           mRange == aOther.mRange &&
+           mValue == aOther.mValue;
+  }
+  bool operator!=(const nsMediaExpression& aOther) const {
+    return !(*this == aOther);
+  }
 };
 
 /**
@@ -73,6 +82,18 @@ public:
   void AddExpression(const nsMediaExpression* aExpression,
                      bool aExpressionMatches);
   bool Matches(nsPresContext* aPresContext) const;
+
+  /**
+   * An operator== that implements list equality, which isn't quite as
+   * good as set equality, but catches the trivial equality cases.
+   */
+  bool operator==(const nsMediaQueryResultCacheKey& aOther) const {
+    return mMedium == aOther.mMedium &&
+           mFeatureCache == aOther.mFeatureCache;
+  }
+  bool operator!=(const nsMediaQueryResultCacheKey& aOther) const {
+    return !(*this == aOther);
+  }
 private:
   struct ExpressionEntry {
     // FIXME: if we were better at maintaining invariants about clearing
@@ -80,10 +101,26 @@ private:
     // nsMediaExpression*| instead.
     nsMediaExpression mExpression;
     bool mExpressionMatches;
+
+    bool operator==(const ExpressionEntry& aOther) const {
+      return mExpression == aOther.mExpression &&
+             mExpressionMatches == aOther.mExpressionMatches;
+    }
+    bool operator!=(const ExpressionEntry& aOther) const {
+      return !(*this == aOther);
+    }
   };
   struct FeatureEntry {
     const nsMediaFeature *mFeature;
     InfallibleTArray<ExpressionEntry> mExpressions;
+
+    bool operator==(const FeatureEntry& aOther) const {
+      return mFeature == aOther.mFeature &&
+             mExpressions == aOther.mExpressions;
+    }
+    bool operator!=(const FeatureEntry& aOther) const {
+      return !(*this == aOther);
+    }
   };
   nsCOMPtr<nsIAtom> mMedium;
   nsTArray<FeatureEntry> mFeatureCache;