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During print preview user can choose a custom page range for printing.
This can easily be less than the entire document.  The recent change
for concurrent PDF composition [1] erroneously always expected the
full document to be collected, which fails with a hung preview if the
user selects a custom page range.

Correct this by updating the PrintRenderFrameHelper to pass along only
the number of pages rendered for the page selection.

[1] https://crrev.com/c/1917685

Bug: 1028104
Change-Id: Ic6ecbc09d09a8c7f30bc959b0a3808d66f1274ac
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1935724Reviewed-by: Rebekah Potter <rbpotter@chromium.org>
Commit-Queue: Alan Screen <awscreen@chromium.org>
Cr-Commit-Position: refs/heads/master@{#719263}