content/chromeos: Fix WebKit software rendering in high-device-scale-factors.

content/chromeos: Fix WebKit software rendering in high-device-scale-factors.

The renderer and the browser continue to communicate between each-other in
terms of device-independent pixels. The browser also continues to
communicate with the backing-store in terms of device-independent pixel size.

This CL changes:
 * the skia backing store to make sure it takes device-scale-factor into
   account when creating the canvas and painting.
 * the renderer to make sure it creates a canvas of the right size for webkit.

BUG=127795
TEST=manually

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=140800

[sadrul, 2012-06-04 22:00:28]

A friendly ping! Please let me know if I should merge the changes from
http://codereview.chromium.org/10481005/ into this CL as well.

[sadrul, 2012-06-06 02:36:06]

+sky: Could you please review changes in content/browser/? Thanks!

[sky, 2012-06-06 15:34:38]

http://codereview.chromium.org/10451112/diff/10002/content/browser/renderer_h...
File content/browser/renderer_host/backing_store_skia.cc (right):

http://codereview.chromium.org/10451112/diff/10002/content/browser/renderer_h...
content/browser/renderer_host/backing_store_skia.cc:46: return size().GetArea()
* 4 * device_scale_factor_ * device_scale_factor_;
Any reason you're not using size().Scale(device_..).GetArea() here?

http://codereview.chromium.org/10451112/diff/10002/content/browser/renderer_h...
content/browser/renderer_host/backing_store_skia.cc:80: const gfx::Rect&
copy_rect = copy_rects[i].Scale(device_scale_factor_);
Remove the & here, eg const gfx::Rect copy_rect =

[sadrul, 2012-06-06 15:46:53]

http://codereview.chromium.org/10451112/diff/10002/content/browser/renderer_h...
File content/browser/renderer_host/backing_store_skia.cc (right):

http://codereview.chromium.org/10451112/diff/10002/content/browser/renderer_h...
content/browser/renderer_host/backing_store_skia.cc:46: return size().GetArea()
* 4 * device_scale_factor_ * device_scale_factor_;
On 2012/06/06 15:34:38, sky wrote:
> Any reason you're not using size().Scale(device_..).GetArea() here?

The only reason being I hadn't thought of it. Done. Thanks! :)

http://codereview.chromium.org/10451112/diff/10002/content/browser/renderer_h...
content/browser/renderer_host/backing_store_skia.cc:80: const gfx::Rect&
copy_rect = copy_rects[i].Scale(device_scale_factor_);
On 2012/06/06 15:34:38, sky wrote:
> Remove the & here, eg const gfx::Rect copy_rect =

Done.

[sky, 2012-06-06 15:47:09]

LGTM

[sadrul, 2012-06-06 15:51:58]

Thanks!

+jam: Could you please review the changes in content/renderer/? Thanks!

[jam, 2012-06-06 16:49:00]

lgtm

http://codereview.chromium.org/10451112/diff/14001/content/renderer/render_wi...
File content/renderer/render_widget.cc (right):

http://codereview.chromium.org/10451112/diff/14001/content/renderer/render_wi...
content/renderer/render_widget.cc:116: device_scale_factor_ =
screen_info.verticalDPI / 160;
nit: add a constant for this per the style guide

[sadrul, 2012-06-06 17:05:36]

Thanks!

http://codereview.chromium.org/10451112/diff/14001/content/renderer/render_wi...
File content/renderer/render_widget.cc (right):

http://codereview.chromium.org/10451112/diff/14001/content/renderer/render_wi...
content/renderer/render_widget.cc:116: device_scale_factor_ =
screen_info.verticalDPI / 160;
On 2012/06/06 16:49:01, John Abd-El-Malek wrote:
> nit: add a constant for this per the style guide

Done. (I considered adding the const int in an anonymous namespace, but I looked
at render_view_impl.cc and followed the style there by adding a static const int
instead)

[Nico, 2012-06-06 19:43:37]

http://codereview.chromium.org/10451112/diff/14003/content/renderer/render_wi...
File content/renderer/render_widget.cc (right):

http://codereview.chromium.org/10451112/diff/14003/content/renderer/render_wi...
content/renderer/render_widget.cc:74: static const int kStandardDPI = 160;
(Nit: const has implicit internal linkage, no need for static or unnamed
namespace. Since this has landed, this is just fyi.)