diff -r 000000000000 -r 6474c204b198 layout/style/MediaQueryList.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/layout/style/MediaQueryList.cpp	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,187 @@
+/* vim: set shiftwidth=2 tabstop=8 autoindent cindent expandtab: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/* implements DOM interface for querying and observing media queries */
+
+#include "mozilla/dom/MediaQueryList.h"
+#include "nsPresContext.h"
+#include "nsIMediaList.h"
+#include "nsCSSParser.h"
+#include "nsIDocument.h"
+
+namespace mozilla {
+namespace dom {
+
+MediaQueryList::MediaQueryList(nsPresContext *aPresContext,
+                               const nsAString &aMediaQueryList)
+  : mPresContext(aPresContext),
+    mMediaList(new nsMediaList),
+    mMatchesValid(false)
+{
+  PR_INIT_CLIST(this);
+
+  SetIsDOMBinding();
+
+  nsCSSParser parser;
+  parser.ParseMediaList(aMediaQueryList, nullptr, 0, mMediaList, false);
+}
+
+MediaQueryList::~MediaQueryList()
+{
+  if (mPresContext) {
+    PR_REMOVE_LINK(this);
+  }
+}
+
+NS_IMPL_CYCLE_COLLECTION_CLASS(MediaQueryList)
+
+NS_IMPL_CYCLE_COLLECTION_TRAVERSE_BEGIN(MediaQueryList)
+  NS_IMPL_CYCLE_COLLECTION_TRAVERSE(mPresContext)
+  NS_IMPL_CYCLE_COLLECTION_TRAVERSE(mCallbacks)
+  NS_IMPL_CYCLE_COLLECTION_TRAVERSE_SCRIPT_OBJECTS
+NS_IMPL_CYCLE_COLLECTION_TRAVERSE_END
+
+NS_IMPL_CYCLE_COLLECTION_UNLINK_BEGIN(MediaQueryList)
+  if (tmp->mPresContext) {
+    PR_REMOVE_LINK(tmp);
+    NS_IMPL_CYCLE_COLLECTION_UNLINK(mPresContext)
+  }
+  tmp->RemoveAllListeners();
+  NS_IMPL_CYCLE_COLLECTION_UNLINK_PRESERVED_WRAPPER
+NS_IMPL_CYCLE_COLLECTION_UNLINK_END
+
+NS_IMPL_CYCLE_COLLECTION_TRACE_WRAPPERCACHE(MediaQueryList)
+
+NS_INTERFACE_MAP_BEGIN(MediaQueryList)
+  NS_WRAPPERCACHE_INTERFACE_MAP_ENTRY
+  NS_INTERFACE_MAP_ENTRY(nsISupports)
+  NS_INTERFACE_MAP_ENTRIES_CYCLE_COLLECTION(MediaQueryList)
+NS_INTERFACE_MAP_END
+
+NS_IMPL_CYCLE_COLLECTING_ADDREF(MediaQueryList)
+NS_IMPL_CYCLE_COLLECTING_RELEASE(MediaQueryList)
+
+void
+MediaQueryList::GetMedia(nsAString &aMedia)
+{
+  mMediaList->GetText(aMedia);
+}
+
+bool
+MediaQueryList::Matches()
+{
+  if (!mMatchesValid) {
+    NS_ABORT_IF_FALSE(!HasListeners(),
+                      "when listeners present, must keep mMatches current");
+    RecomputeMatches();
+  }
+
+  return mMatches;
+}
+
+void
+MediaQueryList::AddListener(MediaQueryListListener& aListener)
+{
+  if (!HasListeners()) {
+    // When we have listeners, the pres context owns a reference to
+    // this.  This is a cyclic reference that can only be broken by
+    // cycle collection.
+    NS_ADDREF_THIS();
+  }
+
+  if (!mMatchesValid) {
+    NS_ABORT_IF_FALSE(!HasListeners(),
+                      "when listeners present, must keep mMatches current");
+    RecomputeMatches();
+  }
+
+  for (uint32_t i = 0; i < mCallbacks.Length(); ++i) {
+    if (aListener == *mCallbacks[i]) {
+      // Already registered
+      return;
+    }
+  }
+
+  mCallbacks.AppendElement(&aListener);
+  if (!HasListeners()) {
+    // Append failed; undo the AddRef above.
+    NS_RELEASE_THIS();
+  }
+}
+
+void
+MediaQueryList::RemoveListener(MediaQueryListListener& aListener)
+{
+  for (uint32_t i = 0; i < mCallbacks.Length(); ++i) {
+    if (aListener == *mCallbacks[i]) {
+      mCallbacks.RemoveElementAt(i);
+      if (!HasListeners()) {
+        // See NS_ADDREF_THIS() in AddListener.
+        NS_RELEASE_THIS();
+      }
+      break;
+    }
+  }
+}
+
+void
+MediaQueryList::RemoveAllListeners()
+{
+  bool hadListeners = HasListeners();
+  mCallbacks.Clear();
+  if (hadListeners) {
+    // See NS_ADDREF_THIS() in AddListener.
+    NS_RELEASE_THIS();
+  }
+}
+
+void
+MediaQueryList::RecomputeMatches()
+{
+  if (!mPresContext) {
+    return;
+  }
+
+  mMatches = mMediaList->Matches(mPresContext, nullptr);
+  mMatchesValid = true;
+}
+
+void
+MediaQueryList::MediumFeaturesChanged(NotifyList &aListenersToNotify)
+{
+  mMatchesValid = false;
+
+  if (HasListeners()) {
+    bool oldMatches = mMatches;
+    RecomputeMatches();
+    if (mMatches != oldMatches) {
+      for (uint32_t i = 0, i_end = mCallbacks.Length(); i != i_end; ++i) {
+        HandleChangeData *d = aListenersToNotify.AppendElement();
+        if (d) {
+          d->mql = this;
+          d->callback = mCallbacks[i];
+        }
+      }
+    }
+  }
+}
+
+nsISupports*
+MediaQueryList::GetParentObject() const
+{
+  if (!mPresContext) {
+    return nullptr;
+  }
+  return mPresContext->Document();
+}
+
+JSObject*
+MediaQueryList::WrapObject(JSContext* aCx)
+{
+  return MediaQueryListBinding::Wrap(aCx, this);
+}
+
+} // namespace dom
+} // namespace mozilla