Combined scale factor and delta updates into one call.

When synchronizing page scale values between trees, setting the page scale
factor and deltas seperately means that the observer functions called when
the page scale factor was changed get called with a transient, incorrect
total page scale factor. This CL combines the seperate methods for updating
the page scale factor and page scale delta into one and updated tree
synchronizations to use this new one-shot function. The old methods remain
but call into the newly added method.

BUG=366249

Review URL: https://codereview.chromium.org/315003009

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@276804 0039d316-1c4b-4281-b951-d872f2087c98

cc/trees/layer_tree_host.cc

@@ -342,10 +342,11 @@ void LayerTreeHost::FinishCommitOnImplThread(LayerTreeHostImpl* host_impl) {
     sync_tree->set_sent_page_scale_delta(1.f);
   }
 
-  sync_tree->SetPageScaleFactorAndLimits(page_scale_factor_,
+  sync_tree->SetPageScaleValues(
+      page_scale_factor_,
       min_page_scale_factor_,
-                                         max_page_scale_factor_);
-  sync_tree->SetPageScaleDelta(page_scale_delta / sent_page_scale_delta);
+      max_page_scale_factor_,
+      page_scale_delta / sent_page_scale_delta);
 
   sync_tree->PassSwapPromises(&swap_promise_list_);
 

cc/trees/layer_tree_impl.cc

@@ -194,9 +194,8 @@ void LayerTreeImpl::PushPropertiesTo(LayerTreeImpl* target_tree) {
 
   target_tree->PassSwapPromises(&swap_promise_list_);
 
-  target_tree->SetPageScaleFactorAndLimits(
-      page_scale_factor(), min_page_scale_factor(), max_page_scale_factor());
-  target_tree->SetPageScaleDelta(
+  target_tree->SetPageScaleValues(
+      page_scale_factor(), min_page_scale_factor(), max_page_scale_factor(),
       target_tree->page_scale_delta() / target_tree->sent_page_scale_delta());
   target_tree->set_sent_page_scale_delta(1);
 
@@ -290,43 +289,38 @@ void ForceScrollbarParameterUpdateAfterScaleChange(LayerImpl* current_layer) {
 
 void LayerTreeImpl::SetPageScaleFactorAndLimits(float page_scale_factor,
     float min_page_scale_factor, float max_page_scale_factor) {
-  if (!page_scale_factor)
-    return;
+  SetPageScaleValues(page_scale_factor, min_page_scale_factor,
+      max_page_scale_factor, page_scale_delta_);
+}
 
-  if (min_page_scale_factor == min_page_scale_factor_ &&
-      max_page_scale_factor == max_page_scale_factor_ &&
-      page_scale_factor == page_scale_factor_)
-    return;
+void LayerTreeImpl::SetPageScaleDelta(float delta) {
+  SetPageScaleValues(page_scale_factor_, min_page_scale_factor_,
+      max_page_scale_factor_, delta);
+}
+
+void LayerTreeImpl::SetPageScaleValues(float page_scale_factor,
+      float min_page_scale_factor, float max_page_scale_factor,
+      float page_scale_delta) {
+  bool page_scale_changed =
+      min_page_scale_factor != min_page_scale_factor_ ||
+      max_page_scale_factor != max_page_scale_factor_ ||
+      page_scale_factor != page_scale_factor_;
 
   min_page_scale_factor_ = min_page_scale_factor;
   max_page_scale_factor_ = max_page_scale_factor;
   page_scale_factor_ = page_scale_factor;
 
-  if (root_layer_scroll_offset_delegate_) {
-    root_layer_scroll_offset_delegate_->UpdateRootLayerState(
-        TotalScrollOffset(),
-        TotalMaxScrollOffset(),
-        ScrollableSize(),
-        total_page_scale_factor(),
-        this->min_page_scale_factor(),
-        this->max_page_scale_factor());
-  }
-
-  ForceScrollbarParameterUpdateAfterScaleChange(page_scale_layer());
-}
-
-void LayerTreeImpl::SetPageScaleDelta(float delta) {
-  // Clamp to the current min/max limits.
-  float total = page_scale_factor_ * delta;
+  float total = page_scale_factor_ * page_scale_delta;
   if (min_page_scale_factor_ && total < min_page_scale_factor_)
-    delta = min_page_scale_factor_ / page_scale_factor_;
+    page_scale_delta = min_page_scale_factor_ / page_scale_factor_;
   else if (max_page_scale_factor_ && total > max_page_scale_factor_)
-    delta = max_page_scale_factor_ / page_scale_factor_;
+    page_scale_delta = max_page_scale_factor_ / page_scale_factor_;
 
-  if (delta == page_scale_delta_)
+  if (page_scale_delta_ == page_scale_delta && !page_scale_changed)
     return;
 
-  page_scale_delta_ = delta;
+  if (page_scale_delta_ != page_scale_delta) {
+    page_scale_delta_ = page_scale_delta;
 
     if (IsActiveTree()) {
       LayerTreeImpl* pending_tree = layer_tree_host_impl_->pending_tree();
@@ -338,6 +332,7 @@ void LayerTreeImpl::SetPageScaleDelta(float delta) {
     }
 
     set_needs_update_draw_properties();
+  }
 
   if (root_layer_scroll_offset_delegate_) {
     root_layer_scroll_offset_delegate_->UpdateRootLayerState(
@@ -345,9 +340,11 @@ void LayerTreeImpl::SetPageScaleDelta(float delta) {
         TotalMaxScrollOffset(),
         ScrollableSize(),
         total_page_scale_factor(),
-        min_page_scale_factor(),
-        max_page_scale_factor());
+        min_page_scale_factor_,
+        max_page_scale_factor_);
   }
+
+  ForceScrollbarParameterUpdateAfterScaleChange(page_scale_layer());
 }
 
 gfx::SizeF LayerTreeImpl::ScrollableViewportSize() const {

cc/trees/layer_tree_impl.h

@@ -155,6 +155,9 @@ class CC_EXPORT LayerTreeImpl {
   void SetPageScaleFactorAndLimits(float page_scale_factor,
       float min_page_scale_factor, float max_page_scale_factor);
   void SetPageScaleDelta(float delta);
+  void SetPageScaleValues(float page_scale_factor,
+      float min_page_scale_factor, float max_page_scale_factor,
+      float page_scale_delta);
   float total_page_scale_factor() const {
     return page_scale_factor_ * page_scale_delta_;
   }