M55: [pdf] Defer page unloading in JS callback.

M55: [pdf] Defer page unloading in JS callback.

One of the callbacks from PDFium JavaScript into the embedder is to get the
current page number. In Chromium, this will trigger a call to
CalculateMostVisiblePage that method will determine the visible pages and unload
any non-visible pages. But, if the originating JS is on a non-visible page
we'll delete the page and annotations associated with that page. This will
cause issues as we are currently working with those objects when the JavaScript
returns.

This Cl defers the page unloading triggered by getting the most visible page
until the next event is handled by the Chromium embedder.

BUG=chromium:653090
Review-Url: https://codereview.chromium.org/2418533002
Cr-Commit-Position: refs/heads/master@{#424781}
(cherry picked from commit bf6a6765d44b09c64b8c75d749efb84742a250e7)

Committed: https://chromium.googlesource.com/chromium/src/+/ff05b41fda6ab437bd48d7eaaaf538bf7a60479a

[Lei Zhang, 2016-10-24 20:33:57]

thestig@chromium.org changed reviewers:
+ dsinclair@chromium.org

[Lei Zhang, 2016-10-24 20:33:57]

TBR

[Lei Zhang, 2016-10-24 20:37:53]

Description was changed from

==========
M55: [pdf] Defer page unloading in JS callback.

One of the callbacks from PDFium JavaScript into the embedder is to get the
current page number. In Chromium, this will trigger a call to
CalculateMostVisiblePage that method will determine the visible pages and unload
any non-visible pages. But, if the originating JS is on a non-visible page
we'll delete the page and annotations associated with that page. This will
cause issues as we are currently working with those objects when the JavaScript
returns.

This Cl defers the page unloading triggered by getting the most visible page
until the next event is handled by the Chromium embedder.

BUG=chromium:653090

Review-Url: https://codereview.chromium.org/2418533002
Cr-Commit-Position: refs/heads/master@{#424781}
(cherry picked from commit bf6a6765d44b09c64b8c75d749efb84742a250e7)
==========

to

==========
M55: [pdf] Defer page unloading in JS callback.

One of the callbacks from PDFium JavaScript into the embedder is to get the
current page number. In Chromium, this will trigger a call to
CalculateMostVisiblePage that method will determine the visible pages and unload
any non-visible pages. But, if the originating JS is on a non-visible page
we'll delete the page and annotations associated with that page. This will
cause issues as we are currently working with those objects when the JavaScript
returns.

This Cl defers the page unloading triggered by getting the most visible page
until the next event is handled by the Chromium embedder.

BUG=chromium:653090

Review-Url: https://codereview.chromium.org/2418533002
Cr-Commit-Position: refs/heads/master@{#424781}
(cherry picked from commit bf6a6765d44b09c64b8c75d749efb84742a250e7)

Committed:
https://chromium.googlesource.com/chromium/src/+/ff05b41fda6ab437bd48d7eaaaf5...
==========

[Lei Zhang, 2016-10-24 20:37:57]

Committed patchset #1 (id:1) manually as
ff05b41fda6ab437bd48d7eaaaf538bf7a60479a.