Hide location bar on WebKit programmatic scroll.

cc/top_controls_manager.cc

Index: cc/top_controls_manager.cc
diff --git a/cc/top_controls_manager.cc b/cc/top_controls_manager.cc
index 7c0f03cf3b5bcc25be9ad55829f611f1bb7136ea..ce0c8992050b1b6adc3e5dbe4e293e7a8edfe80e 100644
--- a/cc/top_controls_manager.cc
+++ b/cc/top_controls_manager.cc
@@ -34,35 +34,31 @@ TopControlsManager::TopControlsManager(TopControlsManagerClient* client,
     : client_(client),
       animation_direction_(NO_ANIMATION),
       is_overlay_mode_(false),
-      scroll_readjustment_enabled_(false),
       top_controls_height_(top_controls_height),
       controls_top_offset_(0),
       content_top_offset_(top_controls_height),
-      previous_root_scroll_offset_(0.f) {
+      in_user_scroll_(false) {
   CHECK(client_);
 }
 
 TopControlsManager::~TopControlsManager() {
 }
 
-void TopControlsManager::UpdateDrawPositions() {
-  if (!client_->haveRootScrollLayer())
+void TopControlsManager::ProgrammaticScroll(gfx::Vector2d targetOffset) {
+  if (controls_top_offset_ == -top_controls_height_)
     return;
 
-  // If the scroll position has changed underneath us (i.e. a javascript
-  // scroll), then simulate a scroll that covers the delta.
-  float scroll_total_y = RootScrollLayerTotalScrollY();
-  if (scroll_readjustment_enabled_
-      && scroll_total_y != previous_root_scroll_offset_) {
-    ScrollBy(gfx::Vector2dF(0, scroll_total_y - previous_root_scroll_offset_));
-    StartAnimationIfNecessary();
-    previous_root_scroll_offset_ = RootScrollLayerTotalScrollY();
-  }
+  // We're in a user scroll.
+  if (in_user_scroll_)
+      return;
+
+  ScrollBy(gfx::Vector2dF(0, top_controls_height_));

[Ted C, 2013/01/24 22:01:01]

hmm...so any javascript scroll will attempt to hide the top controls?  This
should definitely do the trick, but I thought it was only supposed to be limited
to scroll(0,0) or scroll(0,1), but I guess maybe that is what you were saying in
the recent meeting where all types of things hide the top controls.

[John Knottenbelt, 2013/01/30 16:08:45]

We can restrict it here to just 0,0 and 0,1 if we decide that this is what we
really want, but I think hiding on any programmatic scroll matches existing
mobile browsers behaviour more closely. 

On 2013/01/24 22:01:01, Ted C wrote:

+  StartAnimationIfNecessary();

[Ted C, 2013/01/24 22:01:01]

The start animation if necessary shouldn't be required as you should also be
hiding it entirely.

If you want it to always hide the controls but animate it, you should be able to
replace both of these lines with this:
SetupAnimation(HIDING_CONTROLS)

[John Knottenbelt, 2013/01/30 16:08:45]

Done.

 }
 
 void TopControlsManager::ScrollBegin() {
   ResetAnimations();
-  scroll_readjustment_enabled_ = false;
+  in_user_scroll_ = true;
 }
 
 gfx::Vector2dF TopControlsManager::ScrollBy(
@@ -113,8 +109,7 @@ gfx::Vector2dF TopControlsManager::ScrollInternal(
 
 void TopControlsManager::ScrollEnd() {
   StartAnimationIfNecessary();
-  previous_root_scroll_offset_ = RootScrollLayerTotalScrollY();
-  scroll_readjustment_enabled_ = true;
+  in_user_scroll_ = false;
 }
 
 void TopControlsManager::Animate(base::TimeTicks monotonic_time) {