Calculate and track display item opaqueness

third_party/WebKit/Source/platform/graphics/paint/DrawingRecorder.h

Index: third_party/WebKit/Source/platform/graphics/paint/DrawingRecorder.h
diff --git a/third_party/WebKit/Source/platform/graphics/paint/DrawingRecorder.h b/third_party/WebKit/Source/platform/graphics/paint/DrawingRecorder.h
index c8e45e6ee2c214dd5dd8322136e17c163cc8ddfe..58163121486c1cb5e00023126b97f17b71602800 100644
--- a/third_party/WebKit/Source/platform/graphics/paint/DrawingRecorder.h
+++ b/third_party/WebKit/Source/platform/graphics/paint/DrawingRecorder.h
@@ -29,6 +29,8 @@ public:
     DrawingRecorder(GraphicsContext&, const DisplayItemClient&, DisplayItem::Type, const FloatRect& cullRect);
     ~DrawingRecorder();
 
+    void setKnownToBeOpaque() { ASSERT(RuntimeEnabledFeatures::slimmingPaintV2Enabled()); m_knownToBeOpaque = true; }
+
 #if ENABLE(ASSERT)
     void setUnderInvalidationCheckingMode(DrawingDisplayItem::UnderInvalidationCheckingMode mode) { m_underInvalidationCheckingMode = mode; }
 #endif
@@ -37,6 +39,10 @@ private:
     GraphicsContext& m_context;
     const DisplayItemClient& m_displayItemClient;
     const DisplayItem::Type m_displayItemType;
+
+    // True if there are no transparent areas. Only used for SlimmingPaintV2.
+    bool m_knownToBeOpaque;
+
 #if ENABLE(ASSERT)
     size_t m_displayItemPosition;
     DrawingDisplayItem::UnderInvalidationCheckingMode m_underInvalidationCheckingMode;