Hide location bar on WebKit programmatic scroll.

content/renderer/render_widget.cc

Index: content/renderer/render_widget.cc
diff --git a/content/renderer/render_widget.cc b/content/renderer/render_widget.cc
index a7cf43788dd38a1b069bf84c47a9837d4e3ba077..cc4b3eb4dc6cf080f8138bba48e4e85737934427 100644
--- a/content/renderer/render_widget.cc
+++ b/content/renderer/render_widget.cc
@@ -1481,6 +1481,13 @@ void RenderWidget::show(WebNavigationPolicy) {
   SetPendingWindowRect(initial_pos_);
 }
 
+void RenderWidget::hideTopControls() {
+  if (!compositor_)

[jamesr, 2013/03/04 21:44:03]

Do you expect this case to be hit?  Why?

[John Knottenbelt, 2013/03/05 16:41:48]

It seems that all method invocations on compositor_ in this file are guarded by
a NULL check.

I would expect that for Chrome on Android, compositor_ would be non-null, as the
call to hideTopControls originates from a WebKit scroll, and I believe that the
compositor_ should already have been set up by then.

For platforms that are not use accelerated compositing, or have it disabled due
to a switch, the compositor_ will be NULL. hideTopControls() method is public on
RenderWidget, so it could still be called from WebKit.

+    return;
+
+  compositor_->layer_tree_host()->hideTopControls();
+}
+
 void RenderWidget::didFocus() {
 }