Adding backgroundColor to WebCompositionUnderline and using it for InlineTextBox drawing.

Source/core/editing/CompositionUnderlineIterator.h

+/*

[yosin_UTC9, 2014/06/06 01:24:27]

nit: Please use below licence header:
http://dev.chromium.org/blink/coding-style#TOC-License

[huangs, 2014/06/06 20:42:28]

Done.

+ * Copyright (C) 2014 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 CompositionUnderlineIterator_h
+#define CompositionUnderlineIterator_h
+
+#include "core/editing/CompositionUnderline.h"
+#include "wtf/Vector.h"
+
+namespace WebCore {
+
+// A visitor class to yield elements of a sorted (by startOffset) list of underlines,
+// visiting only elements that inersect with specified inclusive range [indexLo, indexHi].
+class CompositionUnderlineIterator {
+    WTF_MAKE_NONCOPYABLE(CompositionUnderlineIterator);
+public:
+    CompositionUnderlineIterator(const Vector<CompositionUnderline>& underlines, size_t indexLo, size_t indexHi)
+        : m_underlines(underlines)
+        , m_indexLo(indexLo)
+        , m_indexHi(indexHi)
+        , m_nextIndex(0) { }
+
+    // Finds the next valid element in m_underlines. Ff found, writes the pointer to the
+    // next element to |underlineOut|, and returns true. Otherwise returns false.
+    bool next(const CompositionUnderline** underlineOut);
+
+private:
+    // Assume that elements of |m_underlines| are sorted by |.startOffset|.
+    const Vector<CompositionUnderline>& m_underlines;
+    const size_t m_indexLo;
+    const size_t m_indexHi;
+    size_t m_nextIndex;
+};
+
+} // namespace WebCore
+
+#endif