Add better handling for very, very small promo dialogs.

chrome/android/java/src/org/chromium/chrome/browser/widget/PromoDialogLayout.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.widget;
 
 import android.content.Context;
 import android.support.graphics.drawable.VectorDrawableCompat;
 import android.util.AttributeSet;
 import android.view.View;
@@ skipping 22 matching lines @@
  * + The buttons are always locked to the bottom of the dialog and stack when there isn't enough
  *   room to display them on one row.
  *
  * + If there is no promo illustration, the header text becomes locked to the top of the dialog and
  *   doesn't scroll away.
  */
 public final class PromoDialogLayout extends BoundedLinearLayout {
     /** Content in the dialog that will flip orientation when the screen is wide. */
     private LinearLayout mFlippableContent;
 
+    /** The scrolling container for the scrollable content. */
+    private ViewGroup mScrollingContainer;
+
     /** Content in the dialog that can be scrolled. */
     private LinearLayout mScrollableContent;
 
     /** Illustration that teases the thing being promoted. */
     private ImageView mIllustrationView;
 
     /** View containing the header of the promo. */
     private TextView mHeaderView;
 
     /** View containing the header of the promo. */
     private TextView mFooterView;
 
     /** View containing text explaining the promo. */
     private TextView mSubheaderView;
 
     /** Paramters used to build the promo. */
     private DialogParams mParams;
 
     public PromoDialogLayout(Context context, AttributeSet attrs) {
         super(context, attrs);
     }
 
     @Override
     public void onFinishInflate() {
         mFlippableContent = (LinearLayout) findViewById(R.id.full_promo_content);
+        mScrollingContainer = (ViewGroup) findViewById(R.id.promo_container);
         mScrollableContent = (LinearLayout) findViewById(R.id.scrollable_promo_content);
         mIllustrationView = (ImageView) findViewById(R.id.illustration);
         mHeaderView = (TextView) findViewById(R.id.header);
         mSubheaderView = (TextView) findViewById(R.id.subheader);
 
         super.onFinishInflate();
     }
 
     /** Initializes the dialog contents using the given params.  Should only be called once. */
     void initialize(DialogParams params) {
         assert mParams == null && params != null;
         assert params.headerStringResource != 0;
         assert params.primaryButtonStringResource != 0;
         mParams = params;
 
         if (mParams.drawableResource == 0 && mParams.vectorDrawableResource == 0) {
             // Dialogs with no illustration make the header stay visible at all times instead of
             // scrolling off on small screens.
             ((ViewGroup) mIllustrationView.getParent()).removeView(mIllustrationView);
-            ((ViewGroup) mHeaderView.getParent()).removeView(mHeaderView);
-            addView(mHeaderView, 0);
-
-            // The margins only apply here (after it moves to the root) because the scroll layout it
-            // is normally in has implicit padding.
-            int marginSize =
-                    getContext().getResources().getDimensionPixelSize(R.dimen.dialog_header_margin);
-            ApiCompatibilityUtils.setMarginStart(
-                    (MarginLayoutParams) mHeaderView.getLayoutParams(), marginSize);
-            ApiCompatibilityUtils.setMarginEnd(
-                    (MarginLayoutParams) mHeaderView.getLayoutParams(), marginSize);
         } else if (mParams.vectorDrawableResource != 0) {
             mIllustrationView.setImageDrawable(VectorDrawableCompat.create(
                     getResources(), mParams.vectorDrawableResource, getContext().getTheme()));
         } else {
             mIllustrationView.setImageResource(mParams.drawableResource);
         }
 
         // Create the header.
         mHeaderView.setText(mParams.headerStringResource);
 
@@ skipping 20 matching lines @@
                 DualControlLayout.createButtonForLayout(getContext(), true, primaryString, null));
 
         if (mParams.secondaryButtonStringResource != 0) {
             String secondaryString =
                     getResources().getString(mParams.secondaryButtonStringResource);
             buttonBar.addView(DualControlLayout.createButtonForLayout(
                     getContext(), false, secondaryString, null));
         }
     }
 
+    /**
+     * Determines whether the header layout needs to be adjusted to ensure the scrollable content
+     * is usable in small form factors.
+     *
+     * @return Whether the layout needed to be adjusted.
+     */
+    private boolean fixupHeader() {
+        if (mParams.drawableResource != 0 || mParams.vectorDrawableResource != 0) return false;
+
+        int minScrollHeight =
+                getResources().getDimensionPixelSize(R.dimen.promo_dialog_min_scrollable_height);
+        boolean shouldHeaderScroll = mScrollingContainer.getMeasuredHeight() < minScrollHeight;
+        ViewGroup desiredParent;
+        boolean applyHeaderPadding;
+        if (shouldHeaderScroll) {
+            desiredParent = mScrollableContent;
+            applyHeaderPadding = false;
+        } else {
+            desiredParent = this;
+            applyHeaderPadding = true;
+        }
+        if (mHeaderView.getParent() == desiredParent) return false;
+        ((ViewGroup) mHeaderView.getParent()).removeView(mHeaderView);
+        desiredParent.addView(mHeaderView, 0);
+
+        int startEndPadding = applyHeaderPadding
+                ? getResources().getDimensionPixelSize(R.dimen.promo_dialog_padding)
+                : 0;
+        ApiCompatibilityUtils.setPaddingRelative(
+                mHeaderView, startEndPadding, 0, startEndPadding, 0);
+        return true;
+    }
+
     @Override
     protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
         int availableWidth = MeasureSpec.getSize(widthMeasureSpec);
         int availableHeight = MeasureSpec.getSize(heightMeasureSpec);
 
         if (availableWidth > availableHeight * 1.5) {
             mFlippableContent.setOrientation(LinearLayout.HORIZONTAL);
         } else {
             mFlippableContent.setOrientation(LinearLayout.VERTICAL);
         }
 
         super.onMeasure(widthMeasureSpec, heightMeasureSpec);
+        if (fixupHeader()) super.onMeasure(widthMeasureSpec, heightMeasureSpec);
     }
 
     /** Adds a View to the layout within the scrollable area. */
     void addControl(View control) {
         mScrollableContent.addView(
                 control, new LayoutParams(LayoutParams.MATCH_PARENT, LayoutParams.WRAP_CONTENT));
     }
 }