[PE] Make PaintChunkProperties ctor explicit to avoid errors.

This patch makes PaintChunkProperties ctor explicit so that
PropertyTreeState cannot be accidentally converted to it, instead
requiring explicit construction.

R=chrishtr@chromium.org

Bug: 810958
Cq-Include-Trybots: master.tryserver.blink:linux_trusty_blink_rel;master.tryserver.chromium.linux:linux_layout_tests_slimming_paint_v2
Change-Id: Id3637eb7aea213af42f1802fcba907e1806bc3c1
Reviewed-on: https://chromium-review.googlesource.com/912463Reviewed-by: Chris Harrelson <chrishtr@chromium.org>
Commit-Queue: vmpstr <vmpstr@chromium.org>
Cr-Commit-Position: refs/heads/master@{#535917}

third_party/WebKit/Source/platform/graphics/GraphicsLayer.cpp

@@ -395,8 +395,8 @@ bool GraphicsLayer::PaintWithoutCommit(
   GraphicsContext context(GetPaintController(), disabled_mode, nullptr);
   if (RuntimeEnabledFeatures::SlimmingPaintV175Enabled()) {
     DCHECK(layer_state_) << "No layer state for GraphicsLayer: " << DebugName();
-    GetPaintController().UpdateCurrentPaintChunkProperties(WTF::nullopt,
-                                                           layer_state_->state);
+    GetPaintController().UpdateCurrentPaintChunkProperties(
+        WTF::nullopt, PaintChunkProperties(layer_state_->state));
   }
 
   previous_interest_rect_ = *interest_rect;

third_party/WebKit/Source/platform/graphics/compositing/PaintChunksToCcLayerTest.cpp

@@ -147,7 +147,8 @@ struct TestChunks {
     size_t i = items.size();
     items.AllocateAndConstruct<DrawingDisplayItem>(
         DefaultId().client, DefaultId().type, std::move(record));
-    chunks.emplace_back(i, i + 1, DefaultId(), PropertyTreeState(t, c, e));
+    chunks.emplace_back(i, i + 1, DefaultId(),
+                        PaintChunkProperties(PropertyTreeState(t, c, e)));
   }
 
   Vector<const PaintChunk*> GetChunkList() const {

third_party/WebKit/Source/platform/graphics/paint/PaintChunkProperties.h

@@ -26,7 +26,7 @@ namespace blink {
 struct PLATFORM_EXPORT PaintChunkProperties {
   DISALLOW_NEW_EXCEPT_PLACEMENT_NEW();
 
-  PaintChunkProperties(const PropertyTreeState& state)
+  explicit PaintChunkProperties(const PropertyTreeState& state)
       : property_tree_state(state), backface_hidden(false) {}
 
   PaintChunkProperties()

third_party/WebKit/Source/platform/graphics/paint/PaintRecordBuilder.cpp

@@ -29,7 +29,7 @@ PaintRecordBuilder::PaintRecordBuilder(SkMetaData* meta_data,
 
   if (RuntimeEnabledFeatures::SlimmingPaintV175Enabled()) {
     paint_controller_->UpdateCurrentPaintChunkProperties(
-        WTF::nullopt, PropertyTreeState::Root());
+        WTF::nullopt, PaintChunkProperties(PropertyTreeState::Root()));
   }
 
   const HighContrastSettings* high_contrast_settings =