Fix another inappropriate overscroll glow.

r259729 fixed one bad overscroll glow, but introduced a regression in another
case.  When a scroll amount fell between 0.01 and 0.1, the early break caused
the amount to fail to be subtracted from unused_scroll_delta at all, so all such
scrolls resulted in a glow.

BUG=358093

Review URL: https://codereview.chromium.org/218883005

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@261241 0039d316-1c4b-4281-b951-d872f2087c98

cc/trees/layer_tree_host_impl.cc

@@ -2269,6 +2269,15 @@ bool LayerTreeHostImpl::ScrollBy(const gfx::Point& viewport_point,
       applied_delta = ScrollLayerWithLocalDelta(layer_impl, pending_delta);
     }
 
+    if (layer_impl == InnerViewportScrollLayer()) {
+      unused_root_delta.Subtract(applied_delta);
+      const float kOverscrollEpsilon = 0.01f;
+      if (std::abs(unused_root_delta.x()) < kOverscrollEpsilon)
+        unused_root_delta.set_x(0.0f);
+      if (std::abs(unused_root_delta.y()) < kOverscrollEpsilon)
+        unused_root_delta.set_y(0.0f);
+    }
+
     // If the layer wasn't able to move, try the next one in the hierarchy.
     float move_threshold = 0.1f;
     bool did_move_layer_x = std::abs(applied_delta.x()) > move_threshold;
@@ -2284,15 +2293,6 @@ bool LayerTreeHostImpl::ScrollBy(const gfx::Point& viewport_point,
         break;
     }
 
-    if (layer_impl == InnerViewportScrollLayer()) {
-      unused_root_delta.Subtract(applied_delta);
-      const float kOverscrollEpsilon = 0.01f;
-      if (std::abs(unused_root_delta.x()) < kOverscrollEpsilon)
-        unused_root_delta.set_x(0.0f);
-      if (std::abs(unused_root_delta.y()) < kOverscrollEpsilon)
-        unused_root_delta.set_y(0.0f);
-    }
-
     did_lock_scrolling_layer_ = true;
     if (!should_bubble_scrolls_) {
       active_tree_->SetCurrentlyScrollingLayer(layer_impl);

cc/trees/layer_tree_host_impl_unittest.cc

@@ -3171,10 +3171,7 @@ TEST_F(LayerTreeHostImplTest, OverscrollAlways) {
   EXPECT_EQ(gfx::Vector2dF(0, 10), host_impl_->accumulated_root_overscroll());
 }
 
-TEST_F(LayerTreeHostImplTest, UnnecessaryGlowEffectCallsWhileScrollingUp) {
-  // Edge glow effect should be applicable only upon reaching Edges
-  // of the content. unnecessary glow effect calls shouldn't be
-  // called while scrolling up without reaching the edge of the content.
+TEST_F(LayerTreeHostImplTest, NoOverscrollWhenNotAtEdge) {
   gfx::Size surface_size(100, 100);
   gfx::Size content_size(200, 200);
   scoped_ptr<LayerImpl> root_clip =
@@ -3195,6 +3192,9 @@ TEST_F(LayerTreeHostImplTest, UnnecessaryGlowEffectCallsWhileScrollingUp) {
   host_impl_->active_tree()->DidBecomeActive();
   DrawFrame();
   {
+    // Edge glow effect should be applicable only upon reaching Edges
+    // of the content. unnecessary glow effect calls shouldn't be
+    // called while scrolling up without reaching the edge of the content.
     EXPECT_EQ(InputHandler::ScrollStarted,
               host_impl_->ScrollBegin(gfx::Point(0, 0), InputHandler::Wheel));
     host_impl_->ScrollBy(gfx::Point(), gfx::Vector2dF(0, 100));
@@ -3204,6 +3204,20 @@ TEST_F(LayerTreeHostImplTest, UnnecessaryGlowEffectCallsWhileScrollingUp) {
     EXPECT_EQ(gfx::Vector2dF().ToString(),
               host_impl_->accumulated_root_overscroll().ToString());
     host_impl_->ScrollEnd();
+    // unusedrootDelta should be subtracted from applied delta so that
+    // unwanted glow effect calls are not called.
+    EXPECT_EQ(InputHandler::ScrollStarted,
+              host_impl_->ScrollBegin(gfx::Point(0, 0),
+                                      InputHandler::NonBubblingGesture));
+    EXPECT_EQ(InputHandler::ScrollStarted, host_impl_->FlingScrollBegin());
+    host_impl_->ScrollBy(gfx::Point(), gfx::Vector2dF(0, 20));
+    EXPECT_EQ(gfx::Vector2dF(0.000000f, 17.699997f).ToString(),
+              host_impl_->accumulated_root_overscroll().ToString());
+
+    host_impl_->ScrollBy(gfx::Point(), gfx::Vector2dF(0.02f, -0.01f));
+    EXPECT_EQ(gfx::Vector2dF(0.000000f, 17.699997f).ToString(),
+              host_impl_->accumulated_root_overscroll().ToString());
+    host_impl_->ScrollEnd();
   }
 }