+Weifang, do you own this component? Or know who does?

Hmm... +fukino@ for an initial triage. I find it odd that the Save to Downloads folder is successful, but not Drive. This seems to me to point to a Files issue as the PDF conversion is occurring successfully on the Save to Downloads.

I noticed the same issue in another scenario too.

Chrome OS version: 62.0.3202.9, dev build
Platform version: 9901.7.0 caroline device

Steps To Reproduce:
1. Open Camera App. Take some pictures using camera option.
2. Goto Gallery and click on Print>Save button (Save as PDF).
3. Save to GDrive folder (select Google Drive in Save file as dialog box).
4. Check in Files app> Google Drive folder for this pdf file. It is not saved.

Save to Google drive from Camera app, also doesn't function.

It's reproduced on my kevin, too.
I'm looking into it...

 Issue 762914  has been merged into this issue.

This issue started from https://codereview.chromium.org/2952043002.

In the CL, save-file dialog's allowed path is specified as NATIVE_OR_DRIVE_PATH (not the defalut value, NATIVE).
It seems this makes the difference.

If the allowed_path is NATIVE, the returned path from save-as dialog will be something like /tmp/chrome/u-foo@gmail.com-hash/GCache/v1/files/5e622a83-fc63-456e-97ca-aaaaaaaaaaaa
If the allowed_path is NATIVE_OR_DRIVE_PATH, the returned path can be a virtual path like /special/drive-foo%40gmail.com-hash/root/New Tab.pdf
I guess this virtual path can not be handled in PrintPreviewHandler::FileSelected.

I confirmed that removing the line setting NATIVE_OR_DRIVE_PATH fixed the issue. (I'm not sure if this is the right approach, though)

WIP CL: https://chromium-review.googlesource.com/c/chromium/src/+/662920

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/b52144f5179f5296510fefcb3e5dea3891b0bb84

commit b52144f5179f5296510fefcb3e5dea3891b0bb84
Author: Naoki Fukino <fukino@chromium.org>
Date: Wed Sep 13 04:27:12 2017

Print Preview: Requires native paths to write PDF files.

Fixing a regression by https://codereview.chromium.org/2952043002/.
Print Preview requires native paths to write PDF files.
I explicitly set NATIVE_PATH as the restriction for save-as dialog, and added a comment about the
Google Drive handling of Chrome OS save-as dialog as it is a bit tricky.

Bug:  761576 
Change-Id: Ibabd428e26cfd0d96a1f65dadc5c0fa4b565e956
Reviewed-on: https://chromium-review.googlesource.com/662920
Reviewed-by: Lei Zhang <thestig@chromium.org>
Reviewed-by: Ryo Hashimoto <hashimoto@chromium.org>
Commit-Queue: Naoki Fukino <fukino@chromium.org>
Cr-Commit-Position: refs/heads/master@{#501541}
[modify] https://crrev.com/b52144f5179f5296510fefcb3e5dea3891b0bb84/chrome/browser/ui/webui/print_preview/print_preview_handler.cc

Requesting a merge to M62 (and M61 if possible).
Without the fix, "Save as PDF" in print preview does not work for Google Drive at all.
The fix (a single-line change) should be safe.

This bug requires manual review: Request affecting a post-stable build
Please contact the milestone owner if you have questions.
Owners: amineer@(Android), cmasso@(iOS), ketakid@(ChromeOS), govind@(Desktop)

For more details visit https://www.chromium.org/issue-tracking/autotriage - Your friendly Sheriffbot

Consider this merge approved for 62, pending the CL making it through the Chrome OS PFQ on ToT.

Approving merge to M61 and M62.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/125d6aa8d52468352aa93a9580b3f838d2924572

commit 125d6aa8d52468352aa93a9580b3f838d2924572
Author: Naoki Fukino <fukino@chromium.org>
Date: Thu Sep 14 00:12:44 2017

Print Preview: Requires native paths to write PDF files.

Fixing a regression by https://codereview.chromium.org/2952043002/.
Print Preview requires native paths to write PDF files.
I explicitly set NATIVE_PATH as the restriction for save-as dialog, and added a comment about the
Google Drive handling of Chrome OS save-as dialog as it is a bit tricky.

Bug:  761576 
Change-Id: Ibabd428e26cfd0d96a1f65dadc5c0fa4b565e956
Reviewed-on: https://chromium-review.googlesource.com/662920
Reviewed-by: Lei Zhang <thestig@chromium.org>
Reviewed-by: Ryo Hashimoto <hashimoto@chromium.org>
Commit-Queue: Naoki Fukino <fukino@chromium.org>
Cr-Original-Commit-Position: refs/heads/master@{#501541}(cherry picked from commit b52144f5179f5296510fefcb3e5dea3891b0bb84)
Reviewed-on: https://chromium-review.googlesource.com/666397
Reviewed-by: Naoki Fukino <fukino@chromium.org>
Cr-Commit-Position: refs/branch-heads/3202@{#213}
Cr-Branched-From: fa6a5d87adff761bc16afc5498c3f5944c1daa68-refs/heads/master@{#499098}
[modify] https://crrev.com/125d6aa8d52468352aa93a9580b3f838d2924572/chrome/browser/ui/webui/print_preview/print_preview_handler.cc

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/2e3cb0ad85d35340afacc41ed16694d307cb4085

commit 2e3cb0ad85d35340afacc41ed16694d307cb4085
Author: Naoki Fukino <fukino@chromium.org>
Date: Thu Sep 14 00:14:54 2017

Print Preview: Requires native paths to write PDF files.

Fixing a regression by https://codereview.chromium.org/2952043002/.
Print Preview requires native paths to write PDF files.
I explicitly set NATIVE_PATH as the restriction for save-as dialog, and added a comment about the
Google Drive handling of Chrome OS save-as dialog as it is a bit tricky.

Bug:  761576 
Change-Id: Ibabd428e26cfd0d96a1f65dadc5c0fa4b565e956
Reviewed-on: https://chromium-review.googlesource.com/662920
Reviewed-by: Lei Zhang <thestig@chromium.org>
Reviewed-by: Ryo Hashimoto <hashimoto@chromium.org>
Commit-Queue: Naoki Fukino <fukino@chromium.org>
Cr-Original-Commit-Position: refs/heads/master@{#501541}(cherry picked from commit b52144f5179f5296510fefcb3e5dea3891b0bb84)
Reviewed-on: https://chromium-review.googlesource.com/666417
Reviewed-by: Naoki Fukino <fukino@chromium.org>
Cr-Commit-Position: refs/branch-heads/3163@{#1195}
Cr-Branched-From: ff259bab28b35d242e10186cd63af7ed404fae0d-refs/heads/master@{#488528}
[modify] https://crrev.com/2e3cb0ad85d35340afacc41ed16694d307cb4085/chrome/browser/ui/webui/print_preview/print_preview_handler.cc

Verified on M64 dev build (10109.0.0, 64.0.3261.0).