Fix composited toolbar in incorrect position for Chrome Home

Previously resize events did not explicitly trigger renders from the
compositor. This went unnoticed because most of the UI existed at
the top of the screen which was largely unaffected by the resize
event. Now, the ToolbarSceneLayer is responsible for requesting
renders when it is at the bottom of the screen.

BUG=698111

Review-Url: https://codereview.chromium.org/2730183002
Cr-Commit-Position: refs/heads/master@{#455781}

chrome/android/java/src/org/chromium/chrome/browser/compositor/scene_layer/ToolbarSceneLayer.java

@@ -18,6 +18,7 @@ import org.chromium.chrome.browser.compositor.layouts.eventfilter.EventFilter;
 import org.chromium.chrome.browser.compositor.overlays.SceneOverlay;
 import org.chromium.chrome.browser.device.DeviceClassManager;
 import org.chromium.chrome.browser.fullscreen.ChromeFullscreenManager;
+import org.chromium.chrome.browser.util.FeatureUtilities;
 import org.chromium.chrome.browser.widget.ClipDrawableProgressBar.DrawingInfo;
 import org.chromium.chrome.browser.widget.ControlContainer;
 import org.chromium.ui.base.DeviceFormFactor;
@@ -164,8 +165,12 @@ public class ToolbarSceneLayer extends SceneOverlayLayer implements SceneOverlay
     }
 
     @Override
-    public void onSizeChanged(float width, float height, float visibleViewportOffsetY,
-            int orientation) {}
+    public void onSizeChanged(
+            float width, float height, float visibleViewportOffsetY, int orientation) {
+        // If Chrome Home is enabled, a size change means the toolbar is now in a different
+        // location so a render is needed.
+        if (FeatureUtilities.isChromeHomeEnabled()) mRenderHost.requestRender();
+    }
 
     @Override
     public void getVirtualViews(List<VirtualView> views) {}