Update Memory.RendererUsed only after Blink is initialized

Update Memory.RendererUsed only after Blink is initialized

Yak shaving to land https://codereview.chromium.org/380533003/

Before the patch, |MemoryObserver| called |GetMemoryUsageKB()| without
any check, which is only valid after webkit is initialized.
GetMemoryUsageKB queries |v8::Isolate::GetCurrent()| internally, but the
query fails on DCHECK on debug builds.

This patch moves the |MemoryObserver| instantiation inside |RenderThreadImpl::EnsureWebKitInitialized|.

BUG=None

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=282321

[kouhei (in TOK), 2014-07-09 04:55:04]

jochen: Would you take a look?

[jochen (gone - plz use gerrit), 2014-07-09 09:16:17]

On 2014/07/09 at 04:55:04, kouhei wrote:
> jochen: Would you take a look?

why not just install the observer once blink is initialized?

[kouhei (in TOK), 2014-07-09 09:45:34]

On 2014/07/09 09:16:17, jochen wrote:
> On 2014/07/09 at 04:55:04, kouhei wrote:
> > jochen: Would you take a look?
> 
> why not just install the observer once blink is initialized?

Makes sense. I moved |MemoryObserver| instantiation to inside
|EnsureWebKitInitialized|.
PTAL.

[jochen (gone - plz use gerrit), 2014-07-09 09:50:01]

On 2014/07/09 at 09:45:34, kouhei wrote:
> On 2014/07/09 09:16:17, jochen wrote:
> > On 2014/07/09 at 04:55:04, kouhei wrote:
> > > jochen: Would you take a look?
> > 
> > why not just install the observer once blink is initialized?
> 
> Makes sense. I moved |MemoryObserver| instantiation to inside
|EnsureWebKitInitialized|.
> PTAL.

maybe also remove it again before we shutdown blink?

[kouhei (in TOK), 2014-07-10 05:41:59]

On 2014/07/09 09:50:01, jochen wrote:
> On 2014/07/09 at 09:45:34, kouhei wrote:
> > On 2014/07/09 09:16:17, jochen wrote:
> > > On 2014/07/09 at 04:55:04, kouhei wrote:
> > > > jochen: Would you take a look?
> > > 
> > > why not just install the observer once blink is initialized?
> > 
> > Makes sense. I moved |MemoryObserver| instantiation to inside
> |EnsureWebKitInitialized|.
> > PTAL.
> 
> maybe also remove it again before we shutdown blink?

Done.

[jochen (gone - plz use gerrit), 2014-07-10 11:19:58]

lgtm

[kouhei (in TOK), 2014-07-10 11:28:09]

Thanks for review!

[kouhei (in TOK), 2014-07-10 11:28:12]

The CQ bit was checked by kouhei@chromium.org

[commit-bot: I haz the power, 2014-07-10 11:29:01]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/kouhei@chromium.org/380603002/40001

[commit-bot: I haz the power, 2014-07-10 12:52:58]

Change committed as 282321