Adding VisualConstraintsWithMetricsAndOptions()

ios/chrome/browser/ui/uikit_ui_util.mm

Index: ios/chrome/browser/ui/uikit_ui_util.mm
diff --git a/ios/chrome/browser/ui/uikit_ui_util.mm b/ios/chrome/browser/ui/uikit_ui_util.mm
index 6c9308aeb02af884b2fe02a90a9e75e4c45ff185..edd8f2da146e8709366d96efc0edcb451b2ce902 100644
--- a/ios/chrome/browser/ui/uikit_ui_util.mm
+++ b/ios/chrome/browser/ui/uikit_ui_util.mm
@@ -570,17 +570,8 @@ void ApplyVisualConstraintsWithMetricsAndOptions(
     NSDictionary* subviewsDictionary,
     NSDictionary* metrics,
     NSLayoutFormatOptions options) {
-  NSMutableArray* layoutConstraints =
-      [NSMutableArray arrayWithCapacity:constraints.count * 3];
-  for (NSString* constraint in constraints) {
-    DCHECK([constraint isKindOfClass:[NSString class]]);
-    [layoutConstraints addObjectsFromArray:
-                           [NSLayoutConstraint
-                               constraintsWithVisualFormat:constraint
-                                                   options:options
-                                                   metrics:metrics
-                                                     views:subviewsDictionary]];
-  }
+  NSArray* layoutConstraints = VisualConstraintsWithMetricsAndOptions(
+      constraints, subviewsDictionary, metrics, options);
   [NSLayoutConstraint activateConstraints:layoutConstraints];
 }
 
@@ -594,6 +585,32 @@ void ApplyVisualConstraintsWithMetricsAndOptions(
                                               metrics, options);
 }
 
+NSArray* VisualConstraintsWithMetrics(NSArray* constraints,
+                                      NSDictionary* subviewsDictionary,
+                                      NSDictionary* metrics) {
+  return VisualConstraintsWithMetricsAndOptions(constraints, subviewsDictionary,
+                                                metrics, 0);
+}
+
+NSArray* VisualConstraintsWithMetricsAndOptions(
+    NSArray* constraints,
+    NSDictionary* subviewsDictionary,
+    NSDictionary* metrics,
+    NSLayoutFormatOptions options) {
+  NSMutableArray* layoutConstraints =
+      [NSMutableArray arrayWithCapacity:constraints.count * 3];

[lpromero, 2017/03/28 11:10:07]

Question for marq: I don't understand the 3. Is it deterministic? A single
visual format string can output way more than 3 constraints.

[marq (ping after 24h), 2017/03/28 12:15:13]

No, it was an estimate. It should probably be documented or just removed, since
I don't know at what point the capacity estimates become optimizations.

[jlebel, 2017/03/29 10:47:17]

Removed as talk offline.

+  for (NSString* constraint in constraints) {
+    DCHECK([constraint isKindOfClass:[NSString class]]);
+    [layoutConstraints addObjectsFromArray:
+                           [NSLayoutConstraint
+                               constraintsWithVisualFormat:constraint
+                                                   options:options
+                                                   metrics:metrics
+                                                     views:subviewsDictionary]];
+  }
+  return layoutConstraints;

[marq (ping after 24h), 2017/03/28 12:15:13]

Missed this: this should return [layoutConstrains copy], so it returns an
immutable array without keeping the mutable array overhead around for no reason.

[jlebel, 2017/03/29 10:47:17]

Done.

+}
+
 void AddSameCenterConstraints(UIView* view1, UIView* view2) {
   AddSameCenterXConstraint(view1, view2);
   AddSameCenterYConstraint(view1, view2);