Refactor viewport initialization logic out of WebViewImpl.

Source/WebKit/chromium/src/ViewportAttributesManager.h

+/*
+ * Copyright (C) 2013 Google Inc. All rights reserved.
+ *
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+ * modification, are permitted provided that the following conditions are
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+ */
+
+#ifndef ViewportAttributesManager_h
+#define ViewportAttributesManager_h
+
+#include "core/dom/ViewportArguments.h"
+#include "core/dom/ViewportAttributes.h"
+#include "core/platform/graphics/IntSize.h"
+
+namespace WebKit {
+
+// This class harmonizes the viewport (particularly page scale) constraints from
+// the meta viewport tag and other sources.
+class ViewportAttributesManager {

[abarth-chromium, 2013/05/20 18:22:25]

Should this object be in Core?  I don't see any client dependencies.

+public:
+    ViewportAttributesManager();
+
+    WebCore::ViewportAttributes defaultConstraints() const;
+
+    // Settings defined in the website's viewport tag, if viewport tag support
+    // is enabled.
+    WebCore::ViewportAttributes pageDefinedConstraints() const { return m_pageDefinedConstraints; }

[abarth-chromium, 2013/05/20 18:22:25]

Should we be returning this object by const reference?  It seems like we're
making some unnecessary copies in a bunch of places.

+    void updatePageDefinedConstraints(const WebCore::ViewportArguments&, WebCore::IntSize viewSize, int layoutFallbackWidth);
+    void adjustPageDefinedConstraintsForAndroidWebView(const WebCore::ViewportArguments&, WebCore::IntSize viewSize, int layoutFallbackWidth, float deviceScaleFactor, bool useWideViewport, bool initializeAtMinimumPageScale);
+
+    // Attributes may also be set from Chromium -- this overrides any
+    // page-defined values.
+    WebCore::ViewportAttributes userAgentConstraints() const { return m_userAgentConstraints; }
+    void setUserAgentConstraints(WebCore::ViewportAttributes);
+
+    // Actual computed values, taking into account the above plus the current
+    // viewport size and document width.
+    WebCore::ViewportAttributes finalConstraints() const { return m_finalConstraints; }
+    void computeFinalConstraints();
+    void adjustFinalConstraintsToContentsSize(WebCore::IntSize viewSize, WebCore::IntSize contentsSize, int nonOverlayScrollbarWidth);
+
+    void didChangeContentsSize(WebCore::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:
+    WebCore::ViewportAttributes m_pageDefinedConstraints;
+    WebCore::ViewportAttributes m_userAgentConstraints;
+    WebCore::ViewportAttributes m_finalConstraints;
+
+    int m_lastContentsWidth;
+
+    bool m_needsReset;
+    bool m_constraintsDirty;
+};
+
+} // namespace WebKit
+
+#endif