Allow scroll events to open custom launcher pages.

ui/app_list/views/app_list_view.cc

Index: ui/app_list/views/app_list_view.cc
diff --git a/ui/app_list/views/app_list_view.cc b/ui/app_list/views/app_list_view.cc
index f2083749f9ab8f7652ca6e3123777a8f1a78193e..803de7431655998b02536284ab7f76515bf36aa6 100644
--- a/ui/app_list/views/app_list_view.cc
+++ b/ui/app_list/views/app_list_view.cc
@@ -338,6 +338,21 @@ bool AppListView::ShouldHandleSystemCommands() const {
   return true;
 }
 
+bool AppListView::ShouldDescendIntoChildForEventHandling(
+    gfx::NativeView child,
+    const gfx::Point& location) {
+  // On the start page, only descend into the search box widget.
+  // Ideally a scroll inside the search box would also be captured, since that's
+  // not meaningful. However, catching that here would also capture clicks on
+  // the microphone icon.

[calamity, 2015/02/12 04:32:24]

You can always add SearchBoxView::OnScroll/Gesture and forward it to the active
content view (which is what keystrokes do right now).

+  ContentsView* contents_view = app_list_main_view_->contents_view();
+  if (contents_view->GetActiveState() == AppListModel::STATE_START)
+    return child == search_box_widget_->GetNativeView();

[calamity, 2015/02/12 04:32:24]

You're also going to need the google logo webview somewhere here... That can
have a clickable image for doodles.

[tapted, 2015/02/13 04:18:41]

Yes. Also: darn.

Turns out matching up |child| with a corresponding WebView in ui/app_list is
super-hard, since there is no content dependency. Patchset 5 has some
exploration of what that would look like (only works on aura).

Gave up on that and now just check against |location| here -- seems to work
pretty well.

+
+  return views::BubbleDelegateView::ShouldDescendIntoChildForEventHandling(
+      child, location);
+}
+
 void AppListView::Prerender() {
   app_list_main_view_->Prerender();
 }
@@ -434,8 +449,6 @@ void AppListView::InitContents(gfx::NativeView parent, int initial_apps_page) {
 void AppListView::InitChildWidgets() {
   DCHECK(search_box_view_);
 
-  app_list_main_view_->InitWidgets();
-
   // Create the search box widget.
   views::Widget::InitParams search_box_widget_params(
       views::Widget::InitParams::TYPE_CONTROL);