Bug 1757126 part 3: Push AccessKey to the parent process cache. r=morgan

Differential Revision: https://phabricator.services.mozilla.com/D151201

accessible/basetypes/Accessible.h

@@ -88,11 +88,18 @@ class KeyBinding {
   KeyBinding() : mKey(0), mModifierMask(0) {}
   KeyBinding(uint32_t aKey, uint32_t aModifierMask)
       : mKey(aKey), mModifierMask(aModifierMask) {}
+  explicit KeyBinding(uint64_t aSerialized) : mSerialized(aSerialized) {}
 
   inline bool IsEmpty() const { return !mKey; }
   inline uint32_t Key() const { return mKey; }
   inline uint32_t ModifierMask() const { return mModifierMask; }
 
+  /**
+   * Serialize this KeyBinding to a uint64_t for use in the parent process
+   * cache. This is simpler than custom IPDL serialization for this simple case.
+   */
+  uint64_t Serialize() { return mSerialized; }
+
   enum Format { ePlatformFormat, eAtkFormat };
 
   /**
@@ -118,8 +125,13 @@ class KeyBinding {
   void ToPlatformFormat(nsAString& aValue) const;
   void ToAtkFormat(nsAString& aValue) const;
 
-  uint32_t mKey;
-  uint32_t mModifierMask;
+  union {
+    struct {
+      uint32_t mKey;
+      uint32_t mModifierMask;
+    };
+    uint64_t mSerialized;
+  };
 };
 
 class Accessible {

accessible/generic/LocalAccessible.cpp

@@ -1467,6 +1467,10 @@ void LocalAccessible::DOMAttributeChanged(int32_t aNameSpaceID,
     SendCache(CacheDomain::GroupInfo, CacheUpdateType::Update);
     return;
   }
+
+  if (aAttribute == nsGkAtoms::accesskey) {
+    mDoc->QueueCacheUpdate(this, CacheDomain::Actions);
+  }
 }
 
 void LocalAccessible::ARIAGroupPosition(int32_t* aLevel, int32_t* aSetSize,
@@ -3516,6 +3520,13 @@ already_AddRefed<AccAttributes> LocalAccessible::BundleFieldsForCache(
         fields->SetAttribute(nsGkAtoms::longdesc, DeleteEntry());
       }
     }
+
+    KeyBinding accessKey = AccessKey();
+    if (!accessKey.IsEmpty()) {
+      fields->SetAttribute(nsGkAtoms::accesskey, accessKey.Serialize());
+    } else if (aUpdateType == CacheUpdateType::Update) {
+      fields->SetAttribute(nsGkAtoms::accesskey, DeleteEntry());
+    }
   }
 
   if (aCacheDomain & CacheDomain::Style) {