Fixing GestureNav on HDPI displays.

Fixing GestureNav on HDPI displays.

The GestireNav screenshot dimensions are density-independent, because when we capture the screenshot we scale it to RVH's bounds: https://code.google.com/p/chromium/codesearch#chromium/src/content/browser/frame_host/navigation_entry_screenshot_manager.cc&q=navigation_entry_sc&sq=package:chromium&type=cs&l=136

Thus we don't need to scale it again when we paint during the overscroll gesture.

BUG=402280
Committed: https://crrev.com/7aa72c87b03a58c50ea88cc000dda7bb16a8edff
Cr-Commit-Position: refs/heads/master@{#292426}

[mfomitchev, 2014-08-26 21:33:58]

mfomitchev@chromium.org changed reviewers:
+ sadrul@chromium.org

[mfomitchev, 2014-08-26 21:33:58]

@sadrul, can you please take the first look?

[sadrul, 2014-08-27 01:54:51]

Has there been a recent change related to this? It used to work correctly on
high-dpi before.

[mfomitchev1, 2014-08-27 02:04:12]

On 2014/08/27 01:54:51, sadrul wrote:
> Has there been a recent change related to this? It used to work correctly on
> high-dpi before.

I couldn't find anything obvious. I guess I could sync to an old revision and
see what's going on there.
That said, looking at the code, it seems to me the new version is doing the
right thing..

[mfomitchev, 2014-08-27 15:58:44]

I tested this on M37, and it appears the scale factor there is reported to be 1
(on the HDPI Surface I used). The code was a bit different, but same semantics:
ui::GetImageScale(ui::GetScaleFactorForNativeView(web_contents_window())).
So it seems it was wrong twice and it cancelled out...

[mfomitchev, 2014-08-27 18:18:17]

mfomitchev@chromium.org changed reviewers:
+ sky@chromium.org

[mfomitchev, 2014-08-27 18:18:18]

+sky@ (might want to bring this into M38)

[sky, 2014-08-27 20:23:08]

LGTM - but wait for Sadrul to be happy too.

[sadrul, 2014-08-28 13:20:05]

LGTM

Perhaps this was caused by https://codereview.chromium.org/462173002 /
https://codereview.chromium.org/461443003

[mfomitchev, 2014-08-28 14:07:18]

The CQ bit was checked by mfomitchev@chromium.org

[commit-bot: I haz the power, 2014-08-28 14:08:28]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/mfomitchev@chromium.org/507083002/1

[commit-bot: I haz the power, 2014-08-28 18:46:11]

Committed patchset #1 (id:1) as ef0c752fb7189143ca4bac13bf82b1b0da27ea59

[commit-bot: I haz the power, 2014-09-10 03:00:59]

Patchset 1 (id:??) landed as
https://crrev.com/7aa72c87b03a58c50ea88cc000dda7bb16a8edff
Cr-Commit-Position: refs/heads/master@{#292426}