CompositorViewHolder is source of truth for viewports

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

Index: chrome/android/java/src/org/chromium/chrome/browser/compositor/layouts/LayoutManagerHost.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/compositor/layouts/LayoutManagerHost.java b/chrome/android/java/src/org/chromium/chrome/browser/compositor/layouts/LayoutManagerHost.java
index f7063f1c9a25cf7566159d364ecd9ce87173f53a..27cdba3e85aa0fe3ed0df86f6d7e4c1a52e1d09f 100644
--- a/chrome/android/java/src/org/chromium/chrome/browser/compositor/layouts/LayoutManagerHost.java
+++ b/chrome/android/java/src/org/chromium/chrome/browser/compositor/layouts/LayoutManagerHost.java
@@ -5,6 +5,7 @@
 package org.chromium.chrome.browser.compositor.layouts;
 
 import android.content.Context;
+import android.graphics.RectF;
 import android.view.View;
 
 import org.chromium.chrome.browser.compositor.TitleCache;
@@ -45,6 +46,24 @@ public interface LayoutManagerHost {
     int getHeight();
 
     /**
+     * Get the window's viewport.
+     * @param outRect The RectF object to write the result to.
+     */
+    void getWindowViewport(RectF outRect);
+
+    /**
+     * Get the visible viewport. This viewport accounts for the height of the browser controls.
+     * @param outRect The RectF object to write the result to.
+     */
+    void getVisibleViewport(RectF outRect);
+
+    /**
+     * @return The height of the screen minus the height of the top and bottom browser controls
+     *         when not hidden.
+     */
+    float getHeightMinusBrowserControls();
+
+    /**
      * @return The associated {@link LayoutRenderHost} to be used from the GL Thread.
      */
     LayoutRenderHost getLayoutRenderHost();