Remove usage of Tab's |url| property from TabUsageRecorder.

ios/chrome/browser/metrics/tab_usage_recorder.mm

Index: ios/chrome/browser/metrics/tab_usage_recorder.mm
diff --git a/ios/chrome/browser/metrics/tab_usage_recorder.mm b/ios/chrome/browser/metrics/tab_usage_recorder.mm
index 14405ace6728337252047bc10c8f86326abb04e7..537815541b82c3a3ac229a4892612b3212fe68fb 100644
--- a/ios/chrome/browser/metrics/tab_usage_recorder.mm
+++ b/ios/chrome/browser/metrics/tab_usage_recorder.mm
@@ -294,7 +294,7 @@
 bool TabUsageRecorder::ShouldIgnoreTab(Tab* tab) {
   // Do not count chrome:// urls to avoid data noise.  For example, if they were
   // counted, every new tab created would add noise to the page load count.
-  return [tab url].SchemeIs(kChromeUIScheme);
+  return tab.lastCommittedURL.SchemeIs(kChromeUIScheme);

[kkhorimoto, 2017/04/14 20:40:47]

chrome:// URLs are never pending, so lastCommitted should be sufficient.

[Eugene But (OOO till 7-30), 2017/04/14 21:48:09]

WebUI can be a pending URL, so maybe we should check both pending and last
committed?

[kkhorimoto, 2017/05/31 23:06:17]

Done.

 }
 
 bool TabUsageRecorder::TabAlreadyEvicted(Tab* tab) {