Force software layer to redraw when it is resized.

Consider the following sequence of events:
1. The view is initialized with a size of 0x0
2. A frame comes in at a size of 50x50. Nothing is drawn.
3. The view is resized to 50x50.

We should re-draw the full frame at step 3, but we don't. This patch
makes it so that we do.

BUG=358450

Review URL: https://codereview.chromium.org/217283006

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@261465 0039d316-1c4b-4281-b951-d872f2087c98

content/browser/renderer_host/render_widget_host_view_mac.mm

@@ -2274,7 +2274,12 @@ void RenderWidgetHostViewMac::LayoutLayers() {
   // in the layer being anchored to the top-left. Set the layer's frame
   // explicitly, since this is more reliable in practice.
   if (software_layer_) {
-    [software_layer_ setFrame:new_background_frame];
+    bool frame_changed = !CGRectEqualToRect(
+        new_background_frame, [software_layer_ frame]);
+    if (frame_changed) {
+      [software_layer_ setFrame:new_background_frame];
+      [software_layer_ setNeedsDisplay];
+    }
   }
 }