[Android] Speculative fix for crash during overscroll effect creation

content/browser/renderer_host/render_widget_host_view_android.cc

Index: content/browser/renderer_host/render_widget_host_view_android.cc
diff --git a/content/browser/renderer_host/render_widget_host_view_android.cc b/content/browser/renderer_host/render_widget_host_view_android.cc
index 67a3e55bcbd80627e58ea9eeedf5f48103b9e2a5..70566b298c8c87493d5a28f9a40429fba8d0d8a7 100644
--- a/content/browser/renderer_host/render_widget_host_view_android.cc
+++ b/content/browser/renderer_host/render_widget_host_view_android.cc
@@ -1601,6 +1601,7 @@ void RenderWidgetHostViewAndroid::SetContentViewCore(
 
   bool resize = false;
   if (content_view_core != content_view_core_) {
+    overscroll_effect_.reset();
     selection_controller_.reset();
     ReleaseLocksOnSurface();
     resize = true;
@@ -1631,10 +1632,12 @@ void RenderWidgetHostViewAndroid::SetContentViewCore(
   if (!selection_controller_)
     selection_controller_.reset(new TouchSelectionController(this));
 
-  if (!content_view_core_)
-    overscroll_effect_.reset();
-  else if (overscroll_effect_enabled_ && !overscroll_effect_)
+  if (overscroll_effect_enabled_ &&
+      !overscroll_effect_ &&
+      content_view_core_->GetWindowAndroid() &&

[no sievers, 2014/08/25 20:37:36]

 content_view_core_->GetWindowAndroid() == NULL seems like an unexpected bug,
see content_view_core_impl.cc:

ContentViewCoreImpl::ContentViewCoreImpl()
...
DCHECK(window_android_);

and it cannot change.

[jdduke (slow), 2014/08/25 20:40:04]

I figured, so I'll check for a null compositor here, then in
|OnAttachCompositor()| recreate the effect if necessary?

+      content_view_core_->GetWindowAndroid()->GetCompositor()) {
     overscroll_effect_ = CreateOverscrollEffect(content_view_core_);
+  }
 }
 
 void RenderWidgetHostViewAndroid::RunAckCallbacks() {