Add a WebDocument::watchCssSelectors(selectors)

Source/core/dom/CSSSelectorWatch.h

Index: Source/core/dom/CSSSelectorWatch.h
diff --git a/Source/core/dom/CSSSelectorWatch.h b/Source/core/dom/CSSSelectorWatch.h
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+/*
+ * Copyright (C) 2013 Google Inc. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following disclaimer
+ * in the documentation and/or other materials provided with the
+ * distribution.
+ *     * Neither the name of Google Inc. nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#ifndef CSSSelectorWatch_h
+#define CSSSelectorWatch_h
+
+#include "core/css/StyleRule.h"
+#include "core/platform/Supplementable.h"
+#include "core/platform/Timer.h"
+#include "wtf/HashSet.h"
+#include "wtf/RefPtr.h"
+#include "wtf/Vector.h"
+#include "wtf/WeakPtr.h"
+#include "wtf/text/WTFString.h"
+
+namespace WebCore {
+
+class Document;
+class ScriptExecutionContext;
+
+class CSSSelectorWatch : public Supplement<ScriptExecutionContext> {
+public:
+    virtual ~CSSSelectorWatch() { }
+
+    static CSSSelectorWatch& from(Document&);
+
+    void watchCSSSelectors(const Vector<String>& selectors);
+    const Vector<RefPtr<StyleRule> >& watchedCallbackSelectors() const { return m_watchedCallbackSelectors; }
+
+    void updateSelectorMatches(const Vector<String>& removedSelectors, const Vector<String>& addedSelectors);
+
+private:
+    CSSSelectorWatch(Document&);
+    void callbackSelectorChangeTimerFired(Timer<CSSSelectorWatch>*);
+
+    Document& m_document;
+
+    Vector<RefPtr<StyleRule> > m_watchedCallbackSelectors;
+
+    // Maps a CSS selector string with a -webkit-callback property to the number
+    // of matching RenderStyle objects in this document.
+    HashMap<String, int> m_matchingCallbackSelectors;
+    // Selectors are relative to m_matchingCallbackSelectors's contents at
+    // the previous call to selectorMatchChanged.
+    HashSet<String> m_addedSelectors;
+    HashSet<String> m_removedSelectors;
+
+    Timer<CSSSelectorWatch> m_callbackSelectorChangeTimer;
+
+    // When an element is reparented, the new location's style is evaluated after the expriation of the relayout timer.
+    // We don't want to send redundant callbacks to the embedder, so this counter lets us wait another time around the event loop.
+    int m_timerExpirations;
+};
+
+} // namespace WebCore
+
+#endif // CSSSelectorWatch_h