Implement RenderWidgetHostViewAndroid::GetLastScrollOffset

Implement RenderWidgetHostViewAndroid::GetLastScrollOffset

Apparently this code was being hit on Android. This CL implements the scroll
offset the same way it's implemented on other platforms.

BUG=409792
NOTRY=true
TBR=aelias@chromium.org

Committed: https://crrev.com/2fc7bab92c8d1bc81761e15cedd3d355e22edf1e
Cr-Commit-Position: refs/heads/master@{#292956}

[whywhat, 2014-09-02 15:42:18]

avayvod@chromium.org changed reviewers:
+ avayvod@chromium.org

[whywhat, 2014-09-02 15:42:18]

lgtm, though you need to correct the bug number to 409792 (s/30/40)

[whywhat, 2014-09-02 15:42:43]

On 2014/09/02 15:42:18, whywhat wrote:
> lgtm, though you need to correct the bug number to 409792 (s/30/40)

Oh, I can do it :)

[timvolodine, 2014-09-02 15:48:20]

timvolodine@chromium.org changed reviewers:
+ timvolodine@chromium.org

[timvolodine, 2014-09-02 15:48:21]

lgtm

[Fady Samuel, 2014-09-02 16:30:38]

The CQ bit was checked by fsamuel@chromium.org

[commit-bot: I haz the power, 2014-09-02 16:34:17]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/fsamuel@chromium.org/533483004/1

[commit-bot: I haz the power, 2014-09-02 17:18:50]

FYI, CQ is re-trying this CL (attempt #1).
The failing builders are:
  win_chromium_x64_rel_swarming on tryserver.chromium.win
(http://build.chromium.org/p/tryserver.chromium.win/builders/win_chromium_x64_...)

[Fady Samuel, 2014-09-02 17:53:43]

The CQ bit was unchecked by fsamuel@chromium.org

[Fady Samuel, 2014-09-02 17:53:44]

The CQ bit was checked by fsamuel@chromium.org

[commit-bot: I haz the power, 2014-09-02 17:54:18]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/fsamuel@chromium.org/533483004/1

[commit-bot: I haz the power, 2014-09-02 17:55:58]

Committed patchset #1 (id:1) as 65d2af75cb766f14e2173ffe590e7d46c4a33868

[commit-bot: I haz the power, 2014-09-10 03:19:23]

Patchset 1 (id:??) landed as
https://crrev.com/2fc7bab92c8d1bc81761e15cedd3d355e22edf1e
Cr-Commit-Position: refs/heads/master@{#292956}