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Source/core/page/PrintContext.h

Index: Source/core/page/PrintContext.h
diff --git a/Source/core/page/PrintContext.h b/Source/core/page/PrintContext.h
index ea9a3de3f37f7d90fc67868522b50b28b851d058..4e63605d38346bee645fe908301364d026dfd5a0 100644
--- a/Source/core/page/PrintContext.h
+++ b/Source/core/page/PrintContext.h
@@ -48,13 +48,14 @@ public:
     // FIXME: This means that CSS page breaks won't be on page boundary if the size is different than what was passed to begin(). That's probably not always desirable.
     // FIXME: Header and footer height should be applied before layout, not after.
     // FIXME: The printRect argument is only used to determine page aspect ratio, it would be better to pass a FloatSize with page dimensions instead.
-    void computePageRects(const FloatRect& printRect, float headerHeight, float footerHeight, float userScaleFactor, float& outPageHeight, bool allowHorizontalTiling = false);
+    virtual void computePageRects(const FloatRect& printRect, float headerHeight, float footerHeight, float userScaleFactor, float& outPageHeight);
 
     // Deprecated. Page size computation is already in this class, clients shouldn't be copying it.
+    // FIXME: Everyone passes |false| for the second paramer. We should remove the second parameter.
     void computePageRectsWithPageSize(const FloatSize& pageSizeInPixels, bool allowHorizontalTiling);

[Vitaly Buka (NO REVIEWS), 2014/08/13 21:43:44]

virtual, because it's also m_pageRects related

and override with NOTREACHED for ChromePrintContext

 
     // These are only valid after page rects are computed.
-    size_t pageCount() const { return m_pageRects.size(); }
+    virtual size_t pageCount() const { return m_pageRects.size(); }
     const IntRect& pageRect(size_t pageNumber) const { return m_pageRects[pageNumber]; }

[Vitaly Buka (NO REVIEWS), 2014/08/13 21:17:42]

pageRect maybe called with incorrect pageNumber if overrided pageCount() returns
different value.

     const Vector<IntRect>& pageRects() const { return m_pageRects; }

[Vitaly Buka (NO REVIEWS), 2014/08/13 21:17:42]

same

[abarth-chromium, 2014/08/13 21:23:14]

That's true.  What do you recommend?

[Vitaly Buka (NO REVIEWS), 2014/08/13 21:43:44]

maybe 
/*no virtual*/ size_t pageCount() const { return pageRects().size(); }

/*no virtual*/ const IntRect& pageRect(size_t pageNumber) const { return
pageRects()[pageNumber]; }

virtual const Vector<IntRect>& pageRects() const { return m_pageRects; }

and overrides pageRects() only 

[Vitaly Buka (NO REVIEWS), 2014/08/13 21:53:27]

Actually even better to do following
all 3 non virtul with no any overrides in ChromePluginPrintContext:
pageCount(), pageRect(size_t pageNumber), pageRects()

but you just need to change following
ChromePluginPrintContext::computePageRects{
m_pageRects.resize(m_plugin->printBegin(m_printParams))
for each rect in m_pageRects rect.size = IntRect(printRect)
}

ChromePluginPrintContext::m_pageCount can be deleted

@@ -63,7 +64,7 @@ public:
     void begin(float width, float height = 0);

[Vitaly Buka (NO REVIEWS), 2014/08/13 21:17:42]

begin should be virtual for consistency

[abarth-chromium, 2014/08/13 21:23:14]

Will do.

 
     // Return to screen mode.
-    void end();
+    virtual void end();
 
     // Used by layout tests.
     static int pageNumberForElement(Element*, const FloatSize& pageSizeInPixels); // Returns -1 if page isn't found.