Send an ack msg to a parent iframe when setting iframe ids for ChromeVox.

Send an ack msg to a parent iframe when setting iframe ids for ChromeVox.

This fixes a few cases in which ChromeVox gets stuck when entering or exiting an iframe:
- during continuous reading, multiple inter frame messages get sent
- on some iframes, even though there's a valid src, ChromeVox isn't injected; this results in the outer ChromeVox continuously messaging into an iframe with out ChromeVox running. This occurs typically with dymaically loaded iframes.

TEST=manual; create a page with an iframe src='http://www.google.com'; previously, ChromeVox gets stuck trying to enter the iframe. Now, it should skip it. On MacRumors.com, attempt to enter one of the iframes containing YouTube content; perform continuous read immediately before the content. Should no longer get stuck.

Committed: https://crrev.com/76fc11f0408b05ecf3177953401f5a746ef53f61
Cr-Commit-Position: refs/heads/master@{#309460}

[David Tseng, 2014-12-22 18:37:48]

dtseng@chromium.org changed reviewers:
+ dmazzoni@chromium.org

[dmazzoni, 2014-12-22 19:18:26]

Thanks for fixing this!

https://codereview.chromium.org/816343004/diff/1/chrome/browser/resources/chr...
File
chrome/browser/resources/chromeos/chromevox/chromevox/injected/navigation_manager.js
(right):

https://codereview.chromium.org/816343004/diff/1/chrome/browser/resources/chr...
chrome/browser/resources/chromeos/chromevox/chromevox/injected/navigation_manager.js:1182:
this.iframeRetries_ = 0;
This logic doesn't look right - if iframeRetries is less than 5, it won't give
up, and this will reset it to 0 - so it will never get to 5 retries.

[David Tseng, 2014-12-22 19:28:57]

https://codereview.chromium.org/816343004/diff/1/chrome/browser/resources/chr...
File
chrome/browser/resources/chromeos/chromevox/chromevox/injected/navigation_manager.js
(right):

https://codereview.chromium.org/816343004/diff/1/chrome/browser/resources/chr...
chrome/browser/resources/chromeos/chromevox/chromevox/injected/navigation_manager.js:1182:
this.iframeRetries_ = 0;
On 2014/12/22 19:18:25, dmazzoni wrote:
> This logic doesn't look right - if iframeRetries is less than 5, it won't give
> up, and this will reset it to 0 - so it will never get to 5 retries.

You're right; moved this into the inner if above and added also to the callback.

[dmazzoni, 2014-12-22 19:35:01]

lgtm

[David Tseng, 2014-12-22 19:40:53]

The CQ bit was checked by dtseng@chromium.org

[commit-bot: I haz the power, 2014-12-22 19:41:11]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/816343004/20001

[commit-bot: I haz the power, 2014-12-22 20:59:36]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2014-12-22 21:00:26]

Patchset 2 (id:??) landed as
https://crrev.com/76fc11f0408b05ecf3177953401f5a746ef53f61
Cr-Commit-Position: refs/heads/master@{#309460}