Update fxjs README
TBR=dsinclair@chromium.org
Change-Id: I6f2a4a4b39c38a1bcfcf817a5c2aa51414291ad9
Reviewed-on: https://pdfium-review.googlesource.com/33451
Reviewed-by: Tom Sepez <tsepez@chromium.org>
Commit-Queue: Tom Sepez <tsepez@chromium.org>
diff --git a/fxjs/README b/fxjs/README
index a38e746..85c5edf 100644
--- a/fxjs/README
+++ b/fxjs/README
@@ -33,3 +33,11 @@
A FXJSE_CLASS_DESCRIPTOR pointer means to expect an actual v8 function
object, and not an aligned pointer.
+Because PDFium uses V8 for various unrelated purposes, there may be up to
+four v8::Contexts (JS Global Objects) associated with each document. One is
+used by FXJS and holds objects as described by the js_api_reference.pdf
+specification. The others are used by FXJSE.
+
+FXJS requires that it can find itself whatever the current context might
+be through a v8::Context's slot -- even if one of the FXJSE contexts is
+current.
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