Change image document zooming logic.

Change image document zooming logic.

The current zoom logic in image documents interacts badly with use-zoom-for-dsf,
in addition to having some weird behavior already.

This patch changes three things:
1. When loading a large image when page zoom was not 100% the image would start
   at a strange scaling factor until it was clicked. This is fixed.
2. When page zoom is at 100% a large image will always scale to fit the window
   regardless of the device scale factor. Previously with use-zoom-for-dsf on it
   would scale too large for the window.
3. When an image that fits in the window is zoomed in until it doesn't it is no
   longer clickable. Previously it would start acting like a large image, which
   was strange.

Also added a test suite for ImageDocument.

BUG=324086, 644059
Review-Url: https://codereview.chromium.org/2319863006
Cr-Commit-Position: refs/heads/master@{#419867}
(cherry picked from commit f5ff44ae79899d114b4bbf5abdd6e960f856c0d9)

Committed: https://chromium.googlesource.com/chromium/src/+/feb3b0ed99499d6232d2d0d2ce5129c95fa51db0

[Bret, 2016-09-21 23:23:20]

Description was changed from

==========
Change image document zooming logic.

The current zoom logic in image documents interacts badly with use-zoom-for-dsf,
in addition to having some weird behavior already.

This patch changes three things:
1. When loading a large image when page zoom was not 100% the image would start
   at a strange scaling factor until it was clicked. This is fixed.
2. When page zoom is at 100% a large image will always scale to fit the window
   regardless of the device scale factor. Previously with use-zoom-for-dsf on it
   would scale too large for the window.
3. When an image that fits in the window is zoomed in until it doesn't it is no
   longer clickable. Previously it would start acting like a large image, which
   was strange.

Also added a test suite for ImageDocument.

BUG=324086,644059

Review-Url: https://codereview.chromium.org/2319863006
Cr-Commit-Position: refs/heads/master@{#419867}
(cherry picked from commit f5ff44ae79899d114b4bbf5abdd6e960f856c0d9)
==========

to

==========
Change image document zooming logic.

The current zoom logic in image documents interacts badly with use-zoom-for-dsf,
in addition to having some weird behavior already.

This patch changes three things:
1. When loading a large image when page zoom was not 100% the image would start
   at a strange scaling factor until it was clicked. This is fixed.
2. When page zoom is at 100% a large image will always scale to fit the window
   regardless of the device scale factor. Previously with use-zoom-for-dsf on it
   would scale too large for the window.
3. When an image that fits in the window is zoomed in until it doesn't it is no
   longer clickable. Previously it would start acting like a large image, which
   was strange.

Also added a test suite for ImageDocument.

BUG=324086,644059

Review-Url: https://codereview.chromium.org/2319863006
Cr-Commit-Position: refs/heads/master@{#419867}
(cherry picked from commit f5ff44ae79899d114b4bbf5abdd6e960f856c0d9)

Committed:
https://chromium.googlesource.com/chromium/src/+/feb3b0ed99499d6232d2d0d2ce51...
==========

[Bret, 2016-09-21 23:23:23]

Committed patchset #1 (id:1) manually as
feb3b0ed99499d6232d2d0d2ce5129c95fa51db0.