Create the base Custom Context Menu Dialog.

chrome/android/java/src/org/chromium/chrome/browser/contextmenu/TabularContextMenuViewPager.java

Index: chrome/android/java/src/org/chromium/chrome/browser/contextmenu/TabularContextMenuViewPager.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/contextmenu/TabularContextMenuViewPager.java b/chrome/android/java/src/org/chromium/chrome/browser/contextmenu/TabularContextMenuViewPager.java
new file mode 100644
index 0000000000000000000000000000000000000000..1589c4e3692c6513c78e172cf58eaf2fa7d85f1f
--- /dev/null
+++ b/chrome/android/java/src/org/chromium/chrome/browser/contextmenu/TabularContextMenuViewPager.java
@@ -0,0 +1,55 @@
+// 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.contextmenu;
+
+import android.content.Context;
+import android.support.v4.view.ViewPager;
+import android.util.AttributeSet;
+import android.view.View;
+
+import org.chromium.chrome.R;
+
+/**
+ * When there is more than one view for the context menu to display, it wraps the display in a view
+ * pager.
+ */
+public class TabularContextMenuViewPager extends ViewPager {
+    public TabularContextMenuViewPager(Context context) {
+        super(context);
+    }
+
+    public TabularContextMenuViewPager(Context context, AttributeSet attrs) {
+        super(context, attrs);
+    }
+
+    /**
+     * Used to show the full ViewPager dialog. Without this the dialog would have no height or
+     * width.
+     */
+    @Override
+    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
+        int maxHeight = 0;
+        int tabHeight = 0;
+        if (getChildCount() > 0) {

[Ted C, 2017/03/24 04:32:53]

I don't think you need this check as the for loop just won't do anything if
child count == 0

[JJ, 2017/03/25 01:40:26]

Whoops you're right

+            for (int i = 0; i < getChildCount(); i++) {
+                View child = getChildAt(i);
+                child.measure(widthMeasureSpec,
+                        MeasureSpec.makeMeasureSpec(maxHeight, MeasureSpec.UNSPECIFIED));
+                int measuredHeight = child.getMeasuredHeight();
+
+                // The ViewPager also considers the tab layout one of its children, and needs to be
+                // treated separately from getting the largest height.
+                if (child.getId() == R.id.tab_layout && child.getVisibility() != GONE) {
+                    tabHeight = measuredHeight;
+                } else {
+                    maxHeight = Math.max(maxHeight, child.getMeasuredHeight());
+                }
+            }
+        }
+        maxHeight += tabHeight;
+        heightMeasureSpec = MeasureSpec.makeMeasureSpec(maxHeight, MeasureSpec.EXACTLY);

[Ted C, 2017/03/24 04:32:54]

what happens if this is larger than the screen dimen again?

[JJ, 2017/03/25 01:40:26]

Again nothing. The Dialog does not go bigger than the screen.

+        super.onMeasure(widthMeasureSpec, heightMeasureSpec);

[Ted C, 2017/03/24 04:32:54]

I wonder if we when we are creating the context menu pages in the previous file,
I think we should just measure the header text + the list view height.  Then max
those across the pages, add it to the tab height as you measure before and then
explicitly set the height of the popup (bounded on screen dimens).  Then I
"don't" think you should need this.

[JJ, 2017/03/25 01:40:25]

That's a good thought. I tried to something with this but then I realized how
this won't work when we get an image that has to remeasure the height. As a
result I don't think we should go through this path? Tell me if you feel free
differently.

[Ted C, 2017/03/27 20:53:33]

In the design spec, it mentions the height never changes for the header for an
image, so I wonder if this is still what we should end up trying to do.

If we ever end up having more than two pages, we might also want to look at
ViewPager#setOffscreenPageLimit to more than 1 to ensure the view traversal is
valid.

If we didn't override onMeasure here or for the listview in the previous file,
what happens if you just set the layout params to the ViewPager to be height
AT_MOST and screen size - image popup padding?  Does it try to fill the whole
space?

Now that I'm thinking about this, I wonder if this is redundant of what
ViewPager#onMeasure does in the first place.

If we just tell it to fill up the most amount of room it can with AT_MOST, does
it iterate across the children and measure them correctly?  It might end up
being more expensive for the listview layouts, but it could be more straight
forward.

[JJ, 2017/03/28 00:09:27]

Awesome, I'll keep that in mind. I'm not sure if this is supposed to be an
actionable change?
Yeah it still tries to fill up all the space regadless of the what we put in our
"AT_MOST" value.
Deleting on Measure entirely means that it will try to fill up the entire
screen.

 
So basically long short onMeasure is required. I'd highly recommend trying out
some other possibliities just in case I missed one.

+    }
+}