[Payments] Add UI elements to secure branding for payments

chrome/android/java/src/org/chromium/chrome/browser/payments/ui/PaymentRequestBottomBar.java

+// Copyright 2017 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.chrome.browser.payments.ui;
+
+import android.content.Context;
+import android.util.AttributeSet;
+import android.view.View;
+import android.view.View.MeasureSpec;
+import android.widget.LinearLayout;
+
+import org.chromium.chrome.R;
+
+/** This class represents a bar to display at the bottom of the payment request UI. */
+public class PaymentRequestBottomBar extends LinearLayout {
+    public PaymentRequestBottomBar(Context context, AttributeSet attrs) {
+        super(context, attrs);
+    }
+
+    @Override
+    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
+        // Views layout_width must be set to match_parent.
+        assert MeasureSpec.getMode(widthMeasureSpec) == MeasureSpec.EXACTLY;
+
+        super.onMeasure(widthMeasureSpec, heightMeasureSpec);
+
+        // Display the logo without product name if there is not enough space.
+        if (findViewById(R.id.space).getMeasuredWidth() == 0) {
+            findViewById(R.id.logo_name).setVisibility(View.GONE);
+            findViewById(R.id.logo).setVisibility(View.VISIBLE);

[gone, 2017/02/17 01:53:54]

This will end up causing another measure pass.  Can you just
setMeasuredDimension(0) on what you're setting to GONE and measure the logo with
what space remains?

[gogerald1, 2017/02/17 17:28:28]

Do not completely get your idea of setMeasuredDimension(0) to save one time of
onMeasure. Do you mean measure each child independently and calculate the space
to decide which one we should show? Anyway, we already did two times onMeasure
here even without setting the logo gone. That might because of the linearlayout.
Sets the logo gone does not increase number of onMeasure in this case. In
addition, onMeasure should be very cheap on this flat linearlayout and set gone
happens very rarely. Might be better to keep it like this for simplicity.

[gone, 2017/02/17 19:02:55]

Simple doesn't always mean correct or efficient.

LinearLayout always does two passes: one to figure out how big everything wants
to be and one to make everything fit within the Layout (weights applied). 
You're saying that you checked that another onMeasure() pass didn't happen with
you changing View visibility here?  I find that extremely odd, given that
visibility changes mean that children need to be re-measured (including the
Space, which will need to expand to account for the now smaller logo).

This code also only ever sets the logo to gone once; you don't account for the
available space increasing, which can happen in split screen mode or if the user
rotates their device.

[gogerald1, 2017/02/17 22:05:38]

Might strange, but that's what I observed, it might could be optimized since the
gone view has fixed width and height. Anyway, measured the bottom bar in
onMeasure instead of using super.onMeasure.

[gogerald1, 2017/02/17 22:05:38]

Done.

+        }
+    }
+}