Make FilteredMemoryPressureCalculator injected dependencies externally owned.

Make FilteredMemoryPressureCalculator injected dependencies externally owned.

This makes final integration with the MemoryPressureMonitor easier, as it will own a single TickClock which can be injected down the entire stack of dependencies.

BUG=520962
Committed: https://crrev.com/1a32b86260006bf52de7d0cd61900aca8031d439
Cr-Commit-Position: refs/heads/master@{#347850}

[chrisha, 2015-09-04 15:25:45]

chrisha@chromium.org changed reviewers:
+ georgesak@chromium.org, grt@chromium.org

[chrisha, 2015-09-04 15:25:45]

(Small refactor to make MemoryPressureMonitor easier to write.)

PTAL?

[grt (UTC plus 2), 2015-09-08 17:34:39]

https://codereview.chromium.org/1317353006/diff/1/components/memory_pressure/...
File components/memory_pressure/filtered_memory_pressure_calculator.h (right):

https://codereview.chromium.org/1317353006/diff/1/components/memory_pressure/...
components/memory_pressure/filtered_memory_pressure_calculator.h:8: #include
"base/time/tick_clock.h"
nit: move this to the .cc file and add a forward decl for base::TickClock.

https://codereview.chromium.org/1317353006/diff/1/components/memory_pressure/...
components/memory_pressure/filtered_memory_pressure_calculator.h:18: class
FilteredMemoryPressureCalculator : public MemoryPressureCalculator {
how is this class used? i don't see any references to it when i git grep for it.

[chrisha, 2015-09-08 19:40:43]

Thanks for the comments. Responses inline.

https://codereview.chromium.org/1317353006/diff/1/components/memory_pressure/...
File components/memory_pressure/filtered_memory_pressure_calculator.h (right):

https://codereview.chromium.org/1317353006/diff/1/components/memory_pressure/...
components/memory_pressure/filtered_memory_pressure_calculator.h:8: #include
"base/time/tick_clock.h"
On 2015/09/08 17:34:39, grt wrote:
> nit: move this to the .cc file and add a forward decl for base::TickClock.

Done.

https://codereview.chromium.org/1317353006/diff/1/components/memory_pressure/...
components/memory_pressure/filtered_memory_pressure_calculator.h:18: class
FilteredMemoryPressureCalculator : public MemoryPressureCalculator {
On 2015/09/08 17:34:39, grt wrote:
> how is this class used? i don't see any references to it when i git grep for
it.

It's not used by anybody yet. It will be used by MemoryPressureMonitor when that
implementation lands (replacing base::MemoryPressureMonitor).

On Win/Linux/CrOS, this class is to be used as a wrapper to a platform-specific
DirectMemoryPressureCalculator implementation, and adds filtering/hysteresis in
a common way. It will be used with a RepeatingTimer that repeatedly asks this
class to calculator a pressure level. On pressure level changes, the
MemoryPressureMonitor that owns the calculator and the timer will then dispatch
events to registered listeners.

(On Android/Mac, the OS provides a signal mechanism and no polling occurs.)

[grt (UTC plus 2), 2015-09-08 20:37:29]

lgtm

https://codereview.chromium.org/1317353006/diff/20001/components/memory_press...
File components/memory_pressure/filtered_memory_pressure_calculator.h (right):

https://codereview.chromium.org/1317353006/diff/20001/components/memory_press...
components/memory_pressure/filtered_memory_pressure_calculator.h:27: static
const int kMinimumTimeBetweenSamplesMs;
FYI: A recent chromium-dev thread suggests that using an enum is better than a
static const member if you don't really need the storage. For example:

enum : int { kMinimumTimeBetweenSamplesMs = NNN };

See
https://groups.google.com/a/chromium.org/d/msg/chromium-dev/hDqJ4KBVqog/jfNPH...
for gory details. No need to make a change right now; just bringing it to your
attention in case you missed the thread.

[chrisha, 2015-09-09 00:14:30]

https://codereview.chromium.org/1317353006/diff/20001/components/memory_press...
File components/memory_pressure/filtered_memory_pressure_calculator.h (right):

https://codereview.chromium.org/1317353006/diff/20001/components/memory_press...
components/memory_pressure/filtered_memory_pressure_calculator.h:27: static
const int kMinimumTimeBetweenSamplesMs;
On 2015/09/08 20:37:29, grt wrote:
> FYI: A recent chromium-dev thread suggests that using an enum is better than a
> static const member if you don't really need the storage. For example:
> 
> enum : int { kMinimumTimeBetweenSamplesMs = NNN };
> 
> See
>
https://groups.google.com/a/chromium.org/d/msg/chromium-dev/hDqJ4KBVqog/jfNPH...
> for gory details. No need to make a change right now; just bringing it to your
> attention in case you missed the thread.

Thanks. There are a handful of such constants throughout this component so I'll
follow up with a cleanup CL. (At no point do I actually need the storage.)

[chrisha, 2015-09-09 00:14:39]

The CQ bit was checked by chrisha@chromium.org

[commit-bot: I haz the power, 2015-09-09 00:15:08]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1317353006/20001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1317353006/20001

[commit-bot: I haz the power, 2015-09-09 00:47:18]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2015-09-09 00:47:50]

Patchset 2 (id:??) landed as
https://crrev.com/1a32b86260006bf52de7d0cd61900aca8031d439
Cr-Commit-Position: refs/heads/master@{#347850}