Improve scrolling performance in OOP PDF

Improve scrolling performance in OOP PDF

This increases the performance of scrolling in OOP PDF by not sending viewport
changes via postMessage every time a scroll event occurs on the page. Instead,
scroll events are sent along with pepper DidChangeView messages, which is a
much more responsive way of updating the scroll position.

Unfortunately this introduces some issues coordinating zoom and scroll events
on the page. When a zoom happens in the container page, a scroll message
might be sent to the plugin via DidChangeView. Then we send a zoom change
message via postMessage. The result is that the zooming and scrolling
happen asynchronously and result in a flickering effect.

To avoid this, we first notify the plugin that we are about to zoom which
causes it to stop reacting to scroll messages. After we have finished zooming
we notify the plugin again so that it can continue reacting to scroll messages.

BUG=386920
Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=279910

[Lei Zhang, 2014-06-23 09:19:41]

lgtm

https://codereview.chromium.org/347763007/diff/1/pdf/out_of_process_instance.cc
File pdf/out_of_process_instance.cc (right):

https://codereview.chromium.org/347763007/diff/1/pdf/out_of_process_instance....
pdf/out_of_process_instance.cc:519: int max_x = document_size_.width() * zoom_ -
plugin_dip_size_.width();
Can we share some of the code with line 369?

[raymes, 2014-06-24 00:41:53]

https://codereview.chromium.org/347763007/diff/1/pdf/out_of_process_instance.cc
File pdf/out_of_process_instance.cc (right):

https://codereview.chromium.org/347763007/diff/1/pdf/out_of_process_instance....
pdf/out_of_process_instance.cc:519: int max_x = document_size_.width() * zoom_ -
plugin_dip_size_.width();
On 2014/06/23 09:19:41, Lei Zhang wrote:
> Can we share some of the code with line 369?

Done.

[raymes, 2014-06-24 00:41:56]

The CQ bit was checked by raymes@chromium.org

[commit-bot: I haz the power, 2014-06-24 00:43:32]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/raymes@chromium.org/347763007/20001

[commit-bot: I haz the power, 2014-06-24 05:10:54]

FYI, CQ is re-trying this CL (attempt #1).
The failing builders are:
  linux_chromium_chromeos_rel on tryserver.chromium
(http://build.chromium.org/p/tryserver.chromium/builders/linux_chromium_chrome...)
  linux_chromium_rel on tryserver.chromium
(http://build.chromium.org/p/tryserver.chromium/builders/linux_chromium_rel/bu...)
  mac_chromium_rel on tryserver.chromium
(http://build.chromium.org/p/tryserver.chromium/builders/mac_chromium_rel/buil...)
  win_chromium_rel on tryserver.chromium
(http://build.chromium.org/p/tryserver.chromium/builders/win_chromium_rel/buil...)

[commit-bot: I haz the power, 2014-06-24 06:30:32]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2014-06-24 06:30:33]

Try jobs failed on following builders:
  linux_chromium_chromeos_rel on tryserver.chromium
(http://build.chromium.org/p/tryserver.chromium/builders/linux_chromium_chrome...)
  linux_chromium_rel on tryserver.chromium
(http://build.chromium.org/p/tryserver.chromium/builders/linux_chromium_rel/bu...)

[raymes, 2014-06-25 23:41:11]

The CQ bit was checked by raymes@chromium.org

[raymes, 2014-06-25 23:41:13]

The CQ bit was unchecked by raymes@chromium.org

[raymes, 2014-06-25 23:59:18]

The CQ bit was checked by raymes@chromium.org

[commit-bot: I haz the power, 2014-06-26 00:03:00]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/raymes@chromium.org/347763007/60001

[commit-bot: I haz the power, 2014-06-26 04:31:50]

FYI, CQ is re-trying this CL (attempt #1).
The failing builders are:
  linux_chromium_gn_rel on tryserver.chromium
(http://build.chromium.org/p/tryserver.chromium/builders/linux_chromium_gn_rel...)

[commit-bot: I haz the power, 2014-06-26 05:45:40]

Change committed as 279910