PDF: Selection Invalidation should compensate for rounding errors.

pdf/pdfium/pdfium_engine.h

Index: pdf/pdfium/pdfium_engine.h
diff --git a/pdf/pdfium/pdfium_engine.h b/pdf/pdfium/pdfium_engine.h
index 449efdf8e01064407cf3708522dd612526d7a7c5..5b46fc06689c0cf185135bc0ae42a0f048a12d27 100644
--- a/pdf/pdfium/pdfium_engine.h
+++ b/pdf/pdfium/pdfium_engine.h
@@ -139,6 +139,10 @@ class PDFiumEngine : public PDFEngine,
     // coordinates.
     std::vector<pp::Rect> GetVisibleSelections() const;
 
+    // Invalidates |selection|, but with |selection| slightly expanded to
+    // compensate for any rounding errors.
+    void Invalidate(const pp::Rect& selection);
+
     PDFiumEngine* const engine_;
     // The origin at the time this object was constructed.
     const pp::Point previous_origin_;