media: Remove SkCanvasVideoRenderer cache invalidation.

media: Remove SkCanvasVideoRenderer cache invalidation.

When VideoFrame carries one native texture, with a GL_TEXTURE_2D target,
we assumed we could avoid caching the created SkImage, since we just used
the texture directly for drawing.
Unfortunately if we're drawing to a software canvas we need to read the pixels
back from the texture, and that is expensive.
Keeping the same SkImage allows Skia to cache the expensive operation.

BUG=521531
Committed: https://crrev.com/771b5cf7667def96ba3de5cb4a4bf38cff12c3b4
Cr-Commit-Position: refs/heads/master@{#345799}

[Daniele Castagna, 2015-08-26 17:11:59]

dcastagna@chromium.org changed reviewers:
+ bsalomon@google.com, dalecurtis@chromium.org, dongseong.hwang@intel.com

[DaleCurtis, 2015-08-27 01:27:46]

lgtm

[Daniele Castagna, 2015-08-27 03:03:06]

The CQ bit was checked by dcastagna@chromium.org

[commit-bot: I haz the power, 2015-08-27 03:03:12]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1320613003/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1320613003/1

[commit-bot: I haz the power, 2015-08-27 04:53:42]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-08-27 04:54:24]

Patchset 1 (id:??) landed as
https://crrev.com/771b5cf7667def96ba3de5cb4a4bf38cff12c3b4
Cr-Commit-Position: refs/heads/master@{#345799}