Avoid integer overflow in LayoutUnit's unary minus operator

third_party/WebKit/Source/platform/LayoutUnitTest.cpp

 /*
  * Copyright (c) 2012, Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
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@@ skipping 238 matching lines @@
 
 TEST(LayoutUnitTest, LayoutUnitFloatOverflow)
 {
     // These should overflow to the max/min according to their sign.
     EXPECT_EQ(intMaxForLayoutUnit, LayoutUnit(176972000.0f).toInt());
     EXPECT_EQ(intMinForLayoutUnit, LayoutUnit(-176972000.0f).toInt());
     EXPECT_EQ(intMaxForLayoutUnit, LayoutUnit(176972000.0).toInt());
     EXPECT_EQ(intMinForLayoutUnit, LayoutUnit(-176972000.0).toInt());
 }
 
+TEST(LayoutUnitTest, UnaryMinusSaturated)

[pdr., 2016/07/20 21:03:55]

What about -(LayoutUnit::min + 1)?

[Xianzhu, 2016/07/20 21:09:10]

This won't be saturated, just a normal negative.

[Xianzhu, 2016/07/20 21:19:20]

Converted this test case to a full UnaryMinus case.

+{
+    EXPECT_EQ(LayoutUnit::max(), -LayoutUnit::min());
+}
+
 } // namespace blink