Create TextViewWithLeading.

ui/android/java/src/org/chromium/ui/widget/TextViewWithLeading.java

+// 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.
+
+package org.chromium.ui.widget;
+
+import android.content.Context;
+import android.content.res.TypedArray;
+import android.util.AttributeSet;
+import android.widget.TextView;
+
+import org.chromium.ui.R;
+
+/**
+ * A TextView with the added leading property.
+ * Leading is the distance between the baselines of successive lines of text (so the space between
+ * rules on ruled paper). This class performs the calculation to setup leading correctly and allows
+ * it to be set in XML. It overwrites android:lineSpacingExtra and android:lineSpacingMultiplier.
+ */
+public class TextViewWithLeading extends TextView {
+    // TODO(peconn): Add a lint check to ensure no lineSpacingExtr or lineSpacingMultiplier.
+    public TextViewWithLeading(Context context, AttributeSet attrs) {
+        super(context, attrs);
+
+        TypedArray a = context.obtainStyledAttributes(attrs, R.styleable.TextViewWithLeading, 0, 0);
+        if (a.hasValue(R.styleable.TextViewWithLeading_leading)) {
+            final float leading = a.getDimension(R.styleable.TextViewWithLeading_leading, 0f);
+            final float oldLeading = getPaint().getFontMetrics(null);

[Ted C, 2016/05/11 17:25:53]

out of curiosity, did you try this on pre-L?

Dan recently pointed out to me that lineSpacingExtra was applied for even single
lines pre L which rarely is what we wanted.

Maybe this accounts for it, but you should quickly test on JB/KK to see if this
looks bad there.

+            setLineSpacing(leading - oldLeading, 1f);
+        }
+
+        a.recycle();
+    }
+}