Make LayerScrollOffsetDelegate updates consistent.

cc/trees/layer_tree_host_impl_unittest.cc

Index: cc/trees/layer_tree_host_impl_unittest.cc
diff --git a/cc/trees/layer_tree_host_impl_unittest.cc b/cc/trees/layer_tree_host_impl_unittest.cc
index 60445095340630fb75ca712d3d2670730d01d540..30ee09f16bc392315a6f04bffecd90394be27a5c 100644
--- a/cc/trees/layer_tree_host_impl_unittest.cc
+++ b/cc/trees/layer_tree_host_impl_unittest.cc
@@ -3030,13 +3030,9 @@ class TestScrollOffsetDelegate : public LayerScrollOffsetDelegate {
 
   virtual ~TestScrollOffsetDelegate() {}
 
-  virtual void SetMaxScrollOffset(
-      const gfx::Vector2dF& max_scroll_offset) OVERRIDE {
-    max_scroll_offset_ = max_scroll_offset;
-  }
-
   virtual void SetTotalScrollOffset(const gfx::Vector2dF& new_value) OVERRIDE {
     last_set_scroll_offset_ = new_value;
+    CheckScrollOffsetWithinBounds();
   }
 
   virtual gfx::Vector2dF GetTotalScrollOffset() OVERRIDE {
@@ -3045,17 +3041,19 @@ class TestScrollOffsetDelegate : public LayerScrollOffsetDelegate {
 
   virtual bool IsExternalFlingActive() const OVERRIDE { return false; }
 
-  virtual void SetTotalPageScaleFactorAndLimits(
-      float page_scale_factor,
-      float min_page_scale_factor,
-      float max_page_scale_factor) OVERRIDE {
+  virtual void UpdateRootLayerState(const gfx::Vector2dF& total_scroll_offset,
+                                    const gfx::Vector2dF& max_scroll_offset,
+                                    const gfx::SizeF& scrollable_size,
+                                    float page_scale_factor,
+                                    float min_page_scale_factor,
+                                    float max_page_scale_factor) OVERRIDE {
+    last_set_scroll_offset_ = total_scroll_offset;
+    max_scroll_offset_ = max_scroll_offset;
+    scrollable_size_ = scrollable_size;
     page_scale_factor_ = page_scale_factor;
     min_page_scale_factor_ = min_page_scale_factor;
     max_page_scale_factor_ = max_page_scale_factor;
-  }
-
-  virtual void SetScrollableSize(const gfx::SizeF& scrollable_size) OVERRIDE {
-    scrollable_size_ = scrollable_size;
+    CheckScrollOffsetWithinBounds();
   }
 
   gfx::Vector2dF last_set_scroll_offset() {
@@ -3087,6 +3085,11 @@ class TestScrollOffsetDelegate : public LayerScrollOffsetDelegate {
   }
 
  private:
+  void CheckScrollOffsetWithinBounds() {
+    DCHECK(last_set_scroll_offset_.x() <= max_scroll_offset_.x());
+    DCHECK(last_set_scroll_offset_.y() <= max_scroll_offset_.y());
+  }
+
   gfx::Vector2dF last_set_scroll_offset_;
   gfx::Vector2dF getter_return_value_;
   gfx::Vector2dF max_scroll_offset_;
@@ -3134,6 +3137,16 @@ TEST_F(LayerTreeHostImplTest, RootLayerScrollOffsetDelegation) {
   EXPECT_EQ(0.5f, scroll_delegate.min_page_scale_factor());
   EXPECT_EQ(4.f, scroll_delegate.max_page_scale_factor());
 
+  // The pinch gesture doesn't put the delegate into a state where the scroll
+  // offset is outside of the scroll range.  (this is verified by DCHECKs in the
+  // delegate).
+  host_impl_->ScrollBegin(gfx::Point(), InputHandler::Gesture);
+  host_impl_->PinchGestureBegin();
+  host_impl_->PinchGestureUpdate(2.f, gfx::Point());
+  host_impl_->PinchGestureUpdate(.5f, gfx::Point());
+  host_impl_->PinchGestureEnd();
+  host_impl_->ScrollEnd();
+
   // Scrolling should be relative to the offset as returned by the delegate.
   gfx::Vector2dF scroll_delta(0.f, 10.f);
   gfx::Vector2dF current_offset(7.f, 8.f);
@@ -3152,6 +3165,7 @@ TEST_F(LayerTreeHostImplTest, RootLayerScrollOffsetDelegation) {
   EXPECT_EQ(current_offset + scroll_delta,
             scroll_delegate.last_set_scroll_offset());
   host_impl_->ScrollEnd();
+  scroll_delegate.set_getter_return_value(gfx::Vector2dF());
 
   // Forces a full tree synchronization and ensures that the scroll delegate
   // sees the correct size of the new tree.