ui: Add methods to clamp Sizes, Points, and Vectors from above or below.

ui/gfx/vector2d.h

Index: ui/gfx/vector2d.h
diff --git a/ui/gfx/vector2d.h b/ui/gfx/vector2d.h
index 6ec37082f3eb1046d8be11bcfacac46e18c0e11c..aa0f1bd9375401632bbaad6c121d34fad785809a 100644
--- a/ui/gfx/vector2d.h
+++ b/ui/gfx/vector2d.h
@@ -40,6 +40,16 @@ class UI_EXPORT Vector2d {
   void operator+=(const Vector2d& other) { Add(other); }
   void operator-=(const Vector2d& other) { Subtract(other); }
 
+  void ClampFromAbove(const Vector2d& other) {
+    x_ = x_ <= other.x_ ? x_ : other.x_;
+    y_ = y_ <= other.y_ ? y_ : other.y_;
+  }
+
+  void ClampFromBelow(const Vector2d& other) {
+    x_ = x_ >= other.x_ ? x_ : other.x_;
+    y_ = y_ >= other.y_ ? y_ : other.y_;
+  }
+
   // Gives the square of the diagonal length of the vector. Since this is
   // cheaper to compute than Length(), it is useful when you want to compare
   // relative lengths of different vectors without needing the actual lengths.