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

ios/chrome/browser/ui/activity_services/share_to_data_builder.mm

Index: ios/chrome/browser/ui/activity_services/share_to_data_builder.mm
diff --git a/ios/chrome/browser/ui/activity_services/share_to_data_builder.mm b/ios/chrome/browser/ui/activity_services/share_to_data_builder.mm
index 3fca21182a26e63ff6fb668deff7fa5c3611d9d4..58ee7118d3e6c8a121dc5a18cf2acd632ab1488f 100644
--- a/ios/chrome/browser/ui/activity_services/share_to_data_builder.mm
+++ b/ios/chrome/browser/ui/activity_services/share_to_data_builder.mm
@@ -31,7 +31,7 @@
   BOOL isPagePrintable = [tab viewForPrinting] != nil;
   ThumbnailGeneratorBlock thumbnailGenerator =
       activity_services::ThumbnailGeneratorForTab(tab);
-  return [[ShareToData alloc] initWithURL:tab.url
+  return [[ShareToData alloc] initWithURL:tab.lastCommittedURL

[kkhorimoto, 2017/04/14 20:35:24]

If a user is attempting to share a page, we can assume they're interested in
sharing the visible content, not a pending load.

[sdefresne, 2017/04/18 15:56:49]

I personally frequently share pages that are still loading (e.g. sending to
"Instapaper" pages that are slow to load because they are under heavy load
because they were featured on a high visibility site like reddit). I think we
should test pending load here.

[Eugene But (OOO till 7-30), 2017/04/18 16:16:47]

I think we should be consistent with other features and platforms. Bookmarks,
f.e. use lastCommitted URL on Desktop and this is something that I would expect
from iOS as well. Because different people may have different opinions, how
about we start a team discussion on this topic? This is product level decision,
not engineering decision.

[kkhorimoto, 2017/05/31 22:12:36]

I agree with Eugene that it should be last committed, but I've sent an email to
bling-team@ for more discussion since this is a product-level decision.

[kkhorimoto, 2017/06/01 19:52:23]

Changed to visible per discussion on email thread.

                                     title:tab.title
                           isOriginalTitle:(tab.originalTitle != nil)
                           isPagePrintable:isPagePrintable