Lobotomize the GPU memory manager

Lobotomize the GPU memory manager

On desktop, always set the memory limit to 256MB, and ask that the renderer
only use that memory to draw content that is near the viewport. The effective
limit prior to this patch was 384MB, but would quickly get cut down as multiple
windows are opened, but would not fall too much lower than 256MB (e.g, 128
on Mac).

On mobile, use all available memory for the current, only, renderer.

Do not take into account unmanaged (e.g, WebGL) memory usage.

BUG=377065
Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=274326

[ccameron, 2014-05-30 00:51:11]

This patch removes a lot of ineffective complexity from the memory manager.

I think that we should find a way to "hibernate" windows that haven't been
updated in a while (free their tiles, and store a compressed "thumbnail" if they
require repainting). This is to reduce the pressure when users open many (dozens
of) windows.

[Ken Russell (switch to Gerrit), 2014-05-31 01:31:15]

LGTM as far as I understand this code, which isn't well.

Would you add yourself as a per-file OWNER of *gpu_memory_manager* in
content/common/gpu in this CL?

The update to content/test/gpu/ looks fine.

[ccameron, 2014-06-02 17:48:14]

On 2014/05/31 01:31:15, Ken Russell wrote:
> LGTM as far as I understand this code, which isn't well.

Yeah, this really spiraled out of control. The remaining code should be easier
to parse.

For a few windows, this keeps everything well under control. For situations
where there are lots of windows open, I think we should hibernate the ones that
update less frequently (see crbug.com/376769) to control memory usage.

I've hit some issues on Mac where people have 40+ windows open and start getting
a bad experience -- the hibernation scheme would do some good there.

> Would you add yourself as a per-file OWNER of *gpu_memory_manager* in
> content/common/gpu in this CL?

Done.

> The update to content/test/gpu/ looks fine.

[ccameron, 2014-06-02 18:18:11]

The CQ bit was checked by ccameron@chromium.org

[commit-bot: I haz the power, 2014-06-02 18:18:50]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/ccameron@chromium.org/308743005/40001

[commit-bot: I haz the power, 2014-06-02 20:55:47]

Change committed as 274326