Check viewport top when sending size change in layouts

This patch adds a check for the top edge of the viewport when
propagating size change events. Previously only two of the three params
were checked for differences when determining whether to send the
event, now we check all three.

Bug: 1136807
Change-Id: Id4a1b7cfac938a6bfd8fd21ae90fb8394d2806db
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2464915Reviewed-by: Mei Liang <meiliang@chromium.org>
Commit-Queue: Matthew Jones <mdjones@chromium.org>
Cr-Commit-Position: refs/heads/master@{#816574}

chrome/android/java/src/org/chromium/chrome/browser/compositor/layouts/LayoutManager.java

@@ -667,6 +667,7 @@ public class LayoutManager implements LayoutUpdateHost, LayoutProvider,
             float previousWidth = getActiveLayout().getWidth();
             float previousHeight = getActiveLayout().getHeight();
 
+            float oldViewportTop = mCachedWindowViewport.top;
             mHost.getWindowViewport(mCachedWindowViewport);
             mHost.getVisibleViewport(mCachedVisibleViewport);
             getActiveLayout().sizeChanged(mCachedVisibleViewport, mCachedWindowViewport,
@@ -675,7 +676,8 @@ public class LayoutManager implements LayoutUpdateHost, LayoutProvider,
 
             float width = mCachedWindowViewport.width() * mPxToDp;
             float height = mCachedWindowViewport.height() * mPxToDp;
-            if (width != previousWidth || height != previousHeight) {
+            if (width != previousWidth || height != previousHeight
+                    || oldViewportTop != mCachedVisibleViewport.top) {
                 for (int i = 0; i < mSceneOverlays.size(); i++) {
                     mSceneOverlays.get(i).onSizeChanged(
                             width, height, mCachedVisibleViewport.top, getOrientation());