Add support of leader_point in NGLayoutOpportunityIterator.

third_party/WebKit/Source/core/layout/ng/ng_constraint_space_test.cc

 // Copyright 2016 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.
 
 #include "core/layout/ng/ng_constraint_space.h"
 
 #include "core/layout/ng/ng_constraint_space.h"
 #include "core/layout/ng/ng_layout_opportunity_iterator.h"
 #include "core/layout/ng/ng_physical_constraint_space.h"
 #include "testing/gtest/include/gtest/gtest.h"
@@ skipping 179 matching lines @@
 
   // 4th Start point
   EXPECT_EQ("0,300 600x50", OpportunityToString(iterator->Next()));
   EXPECT_EQ("0,300 500x100", OpportunityToString(iterator->Next()));
 
   // Iterator is exhausted.
   EXPECT_EQ("(empty)", OpportunityToString(iterator->Next()));
 }
 
 // This test is the same as LayoutOpportunitiesTwoInMiddle with the only
-// difference that NGLayoutOpportunityIterator takes the additional argument
-// origin_point that changes the iterator to return Layout Opportunities that
+// difference that NGLayoutOpportunityIterator takes 2 additional arguments:
+// - origin_point that changes the iterator to return Layout Opportunities that
 // lay after the origin point.
+// - leader_point that together with origin_point creates a temporary exclusion
 //
 // Expected:
 //   Layout opportunity iterator generates the next opportunities:
-//   - 1st Start Point (0, 200): 150x200
-//   - 2nd Start Point (250, 200): 350x150, 250x200
+//   - 1st Start Point (0, 200): 350x150, 250x200
 //   - 3rd Start Point (550, 200): 50x200
 //   - 4th Start Point (0, 300): 600x50, 500x100
 //   All other opportunities that are located before the origin point should be
 //   filtered out.
-TEST(NGConstraintSpaceTest, LayoutOpportunitiesTwoInMiddleWithOrigin) {
+TEST(NGConstraintSpaceTest, LayoutOpportunitiesTwoInMiddleWithOriginAndLeader) {
   NGPhysicalSize physical_size;
   physical_size.width = LayoutUnit(600);
   physical_size.height = LayoutUnit(400);
 
   auto* space =
       ConstructConstraintSpace(HorizontalTopBottom, LeftToRight, physical_size);
   // Add exclusions
   NGLogicalRect exclusion1;
   exclusion1.size = {/* inline_size */ LayoutUnit(100),
                      /* block_size */ LayoutUnit(100)};
   exclusion1.offset = {/* inline_offset */ LayoutUnit(150),
                        /* block_offset */ LayoutUnit(200)};
   space->AddExclusion(exclusion1);
   NGLogicalRect exclusion2;
   exclusion2.size = {/* inline_size */ LayoutUnit(50),
                      /* block_size */ LayoutUnit(50)};
   exclusion2.offset = {/* inline_offset */ LayoutUnit(500),
                        /* block_offset */ LayoutUnit(350)};
   space->AddExclusion(exclusion2);
 
   const NGLogicalOffset origin_point = {LayoutUnit(0), LayoutUnit(200)};
-  auto* iterator = new NGLayoutOpportunityIterator(space, origin_point);
+  const NGLogicalOffset leader_point = {LayoutUnit(250), LayoutUnit(300)};
+  auto* iterator =
+      new NGLayoutOpportunityIterator(space, origin_point, leader_point);
 
   // 1st Start Point
-  EXPECT_EQ("0,200 150x200", OpportunityToString(iterator->Next()));
-
-  // 2nd Start Point
   EXPECT_EQ("250,200 350x150", OpportunityToString(iterator->Next()));
   EXPECT_EQ("250,200 250x200", OpportunityToString(iterator->Next()));
 
-  // 3rd Start Point
+  // 2nd Start Point
   EXPECT_EQ("550,200 50x200", OpportunityToString(iterator->Next()));
 
-  // 4th Start Point
+  // 3rd Start Point
   EXPECT_EQ("0,300 600x50", OpportunityToString(iterator->Next()));
   EXPECT_EQ("0,300 500x100", OpportunityToString(iterator->Next()));
 
   // Iterator is exhausted.
   EXPECT_EQ("(empty)", OpportunityToString(iterator->Next()));
 }
 
 // Verifies that Layout Opportunity iterator ignores the exclusion that is not
 // within constraint space.
 //
@@ skipping 24 matching lines @@
   space->AddExclusion(exclusion);
 
   auto* iterator = space->LayoutOpportunities();
 
   EXPECT_EQ("0,0 600x100", OpportunityToString(iterator->Next()));
   EXPECT_EQ("(empty)", OpportunityToString(iterator->Next()));
 }
 
 }  // namespace
 }  // namespace blink