Reduce delay when showing feedback.

Reduce delay when showing feedback.
Move the toDataURL operation of the canvas containing the screenshot to after we show the feedback page. This will significantly increase the response time from when a user requests feedback to the time that the feedback window is shown.

R=xiyuan@chromium.org
BUG=308414
Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=234660

[xiyuan, 2013-11-12 23:03:21]

https://codereview.chromium.org/61153007/diff/1/chrome/browser/resources/feed...
File chrome/browser/resources/feedback/js/feedback.js (right):

https://codereview.chromium.org/61153007/diff/1/chrome/browser/resources/feed...
chrome/browser/resources/feedback/js/feedback.js:242:
chrome.app.window.current().show();
Should this be moved out of the takeScreenshot callback to complete avoid
waiting on the screenshot capture?

https://codereview.chromium.org/61153007/diff/1/chrome/browser/resources/feed...
chrome/browser/resources/feedback/js/feedback.js:249:
console.log('FEEDBACK_DEBUG: Taken screenshot. Showing window.');
nit: Remove 'Showing window' from the message since the code is moved somewhere
else.

[rkc, 2013-11-12 23:11:04]

https://codereview.chromium.org/61153007/diff/1/chrome/browser/resources/feed...
File chrome/browser/resources/feedback/js/feedback.js (right):

https://codereview.chromium.org/61153007/diff/1/chrome/browser/resources/feed...
chrome/browser/resources/feedback/js/feedback.js:242:
chrome.app.window.current().show();
On 2013/11/12 23:03:22, xiyuan wrote:
> Should this be moved out of the takeScreenshot callback to complete avoid
> waiting on the screenshot capture?

We can't. The screenshot must be taken before the feedback window is shown
otherwise the feedback window will appear in the screenshot, potentially
blocking useful visuals.

The best we can do is that as soon as the screenshot is taken (i.e., we capture
it to the canvas from the video), we show the Feedback window and do the
toDataURL processing (which is quite slow) after the window has shown.

https://codereview.chromium.org/61153007/diff/1/chrome/browser/resources/feed...
chrome/browser/resources/feedback/js/feedback.js:249:
console.log('FEEDBACK_DEBUG: Taken screenshot. Showing window.');
On 2013/11/12 23:03:22, xiyuan wrote:
> nit: Remove 'Showing window' from the message since the code is moved
somewhere
> else.

Already did in patchset #2 :)
Done.

[xiyuan, 2013-11-12 23:16:30]

lgtm

https://codereview.chromium.org/61153007/diff/1/chrome/browser/resources/feed...
File chrome/browser/resources/feedback/js/feedback.js (right):

https://codereview.chromium.org/61153007/diff/1/chrome/browser/resources/feed...
chrome/browser/resources/feedback/js/feedback.js:242:
chrome.app.window.current().show();
On 2013/11/12 23:11:04, Rahul Chaturvedi wrote:
> On 2013/11/12 23:03:22, xiyuan wrote:
> > Should this be moved out of the takeScreenshot callback to complete avoid
> > waiting on the screenshot capture?
> 
> We can't. The screenshot must be taken before the feedback window is shown
> otherwise the feedback window will appear in the screenshot, potentially
> blocking useful visuals.
> 
> The best we can do is that as soon as the screenshot is taken (i.e., we
capture
> it to the canvas from the video), we show the Feedback window and do the
> toDataURL processing (which is quite slow) after the window has shown.

I see.

[rkc, 2013-11-12 23:20:50]

Committed patchset #2 manually as r234660 (presubmit successful).