Reduce delay when showing feedback.

chrome/browser/resources/feedback/js/feedback.js

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 /** @type {string}
  * @const
  */
 var FEEDBACK_LANDING_PAGE =
     'https://www.google.com/support/chrome/go/feedback_confirmation';
 /** @type {number}
@@ skipping 217 matching lines @@
   // Add listener to receive the feedback info object.
   chrome.runtime.onMessage.addListener(function(request, sender, sendResponse) {
     if (request.sentFromEventPage) {
       // TODO(rkc):  Remove logging once crbug.com/284662 is closed.
       console.log('FEEDBACK_DEBUG: Received feedbackInfo.');
       feedbackInfo = request.data;
       $('description-text').textContent = feedbackInfo.description;
       if (feedbackInfo.pageUrl)
         $('page-url-text').value = feedbackInfo.pageUrl;
 
-      takeScreenshot(function(screenshotDataUrl) {
+      takeScreenshot(function(screenshotCanvas) {
+        // We've taken our screenshot, show the feedback page without any
+        // further delay.
+        resizeAppWindow();
+        chrome.app.window.current().show();

[xiyuan, 2013/11/12 23:03:22]

Should this be moved out of the takeScreenshot callback to complete avoid
waiting on the screenshot capture?

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

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.

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

I see.

+
+        var screenshotDataUrl = screenshotCanvas.toDataURL('image/png');
         $('screenshot-image').src = screenshotDataUrl;
         feedbackInfo.screenshot = dataUrlToBlob(screenshotDataUrl);
+
         // TODO(rkc):  Remove logging once crbug.com/284662 is closed.
         console.log('FEEDBACK_DEBUG: Taken screenshot. Showing window.');

[xiyuan, 2013/11/12 23:03:22]

nit: Remove 'Showing window' from the message since the code is moved somewhere
else.

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

Already did in patchset #2 :)
Done.

-        resizeAppWindow();
-        chrome.app.window.current().show();
       });
 
       chrome.feedbackPrivate.getUserEmail(function(email) {
         $('user-email-text').value = email;
       });
 
       chrome.feedbackPrivate.getSystemInformation(function(sysInfo) {
         systemInfo = sysInfo;
       });
 
@@ skipping 42 matching lines @@
       if (windowId == systemInfoWindowId)
         systemInfoWindowId = 0;
     });
     if ($('sysinfo-url')) {
       $('sysinfo-url').onclick = openSystemInfoWindow;
     }
   });
 }
 
 initialize();