Fix bump-scroll on Mac.

This also fixes a bug in the tool-bar position when the window is scrolled.

BUG=411996

Review URL: https://codereview.chromium.org/575303002

Cr-Commit-Position: refs/heads/master@{#295526}

remoting/webapp/fullscreen_v1.js

@@ -79,5 +79,15 @@ remoting.FullscreenAppsV1.prototype.removeListener = function(callback) {
  * @private
  */
 remoting.FullscreenAppsV1.prototype.onFullscreenChanged_ = function() {
-  this.eventSource_.raiseEvent(this.kEventName_, this.isActive());
+  // Querying full-screen immediately after the webkitfullscreenchange
+  // event fires sometimes gives the wrong answer on Mac, perhaps due to
+  // the time taken to animate presentation mode. Since I haven't been able
+  // to isolate the exact repro steps, and we're not planning on using this
+  // API for much longer, this hack will suffice for now.
+  window.setTimeout(
+      /** @this {remoting.FullscreenAppsV1} */
+      function() {
+        this.eventSource_.raiseEvent(this.kEventName_, this.isActive());
+      }.bind(this),
+      500);
 };

remoting/webapp/toolbar.css

@@ -4,7 +4,7 @@
  */
 
 .toolbar-container {
-  position: absolute;
+  position: fixed;
   top: -48px;
   width: 640px;
   -webkit-transition: top 0.15s ease;