Refactor viewport initialization logic out of WebViewImpl.

Source/core/page/PageScaleConstraintsSet.h

+/*
+ * 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 PageScaleConstraintsSet_h
+#define PageScaleConstraintsSet_h
+
+#include "PageScaleConstraints.h"
+#include "core/dom/ViewportArguments.h"
+#include "core/platform/graphics/IntSize.h"
+
+namespace WebCore {
+
+// This class harmonizes the viewport (particularly page scale) constraints from
+// the meta viewport tag and other sources.
+class PageScaleConstraintsSet {
+public:
+    PageScaleConstraintsSet();
+
+    PageScaleConstraints defaultConstraints() const;
+
+    // Settings defined in the website's viewport tag, if viewport tag support
+    // is enabled.
+    const PageScaleConstraints& pageDefinedConstraints() const { return m_pageDefinedConstraints; }
+    void updatePageDefinedConstraints(const ViewportArguments&, IntSize viewSize, int layoutFallbackWidth);
+    void adjustPageDefinedConstraintsForAndroidWebView(const ViewportArguments&, IntSize viewSize, int layoutFallbackWidth, float deviceScaleFactor, bool useWideViewport, bool loadWithOverviewMode);
+
+    // Constraints may also be set from Chromium -- this overrides any
+    // page-defined values.
+    const PageScaleConstraints& userAgentConstraints() const { return m_userAgentConstraints; }
+    void setUserAgentConstraints(const PageScaleConstraints&);
+
+    // Actual computed values, taking into account the above plus the current
+    // viewport size and document width.
+    const PageScaleConstraints& finalConstraints() const { return m_finalConstraints; }
+    void computeFinalConstraints();
+    void adjustFinalConstraintsToContentsSize(IntSize viewSize, IntSize contentsSize, int nonOverlayScrollbarWidth);
+
+    void didChangeContentsSize(IntSize contentsSize, float pageScaleFactor);
+
+    // This should be set to true on each page load to note that the page scale
+    // factor needs to be reset to its initial value.
+    void setNeedsReset(bool);
+    bool needsReset() const { return m_needsReset; }
+
+    // This is set when one of the inputs to finalConstraints changes.
+    bool constraintsDirty() const { return m_constraintsDirty; }
+
+private:
+    PageScaleConstraints m_pageDefinedConstraints;
+    PageScaleConstraints m_userAgentConstraints;
+    PageScaleConstraints m_finalConstraints;
+
+    int m_lastContentsWidth;
+
+    bool m_needsReset;
+    bool m_constraintsDirty;
+};
+
+} // namespace WebCore
+
+#endif // PageScaleConstraintsSet_h