[Squad] Unnecessary use of mutable style in vp propagation.

Also a couple of other places where ComputedStyle could be made
immutable.

Bug: 813068
Change-Id: I7cebac7951adbf65dbb057ef7b75d4ddab62e90c
Reviewed-on: https://chromium-review.googlesource.com/924145
Reviewed-by: Morten Stenshorne <mstensho@chromium.org>
Commit-Queue: Rune Lillesveen <futhark@chromium.org>
Cr-Commit-Position: refs/heads/master@{#537340}

diff --git a/third_party/WebKit/Source/core/css/resolver/StyleResolver.cpp b/third_party/WebKit/Source/core/css/resolver/StyleResolver.cpp
index 4a33b40..ade931f86 100644
--- a/third_party/WebKit/Source/core/css/resolver/StyleResolver.cpp
+++ b/third_party/WebKit/Source/core/css/resolver/StyleResolver.cpp

@@ -623,8 +623,10 @@
   // be propagated from shadow host to distributed node.
   if (state.DistributedToV0InsertionPoint() || element->AssignedSlot()) {
     if (Element* parent = element->parentElement()) {
-      if (ComputedStyle* style_of_shadow_host = parent->MutableComputedStyle())
+      if (const ComputedStyle* style_of_shadow_host =
+              parent->GetComputedStyle()) {
         state.Style()->SetUserModify(style_of_shadow_host->UserModify());
+      }
     }
   }
 

diff --git a/third_party/WebKit/Source/core/dom/Document.cpp b/third_party/WebKit/Source/core/dom/Document.cpp
index c437dcf8..5884994e 100644
--- a/third_party/WebKit/Source/core/dom/Document.cpp
+++ b/third_party/WebKit/Source/core/dom/Document.cpp

@@ -2042,27 +2042,27 @@
   Length scroll_padding_bottom = overflow_style->ScrollPaddingBottom();
   Length scroll_padding_left = overflow_style->ScrollPaddingLeft();
 
-  scoped_refptr<ComputedStyle> viewport_style = GetLayoutView()->MutableStyle();
-  if (viewport_style->GetWritingMode() != root_writing_mode ||
-      viewport_style->Direction() != root_direction ||
-      viewport_style->VisitedDependentColor(GetCSSPropertyBackgroundColor()) !=
+  const ComputedStyle& viewport_style = GetLayoutView()->StyleRef();
+  if (viewport_style.GetWritingMode() != root_writing_mode ||
+      viewport_style.Direction() != root_direction ||
+      viewport_style.VisitedDependentColor(GetCSSPropertyBackgroundColor()) !=
           background_color ||
-      viewport_style->BackgroundLayers() != background_layers ||
-      viewport_style->ImageRendering() != image_rendering ||
-      viewport_style->OverflowAnchor() != overflow_anchor ||
-      viewport_style->OverflowX() != overflow_x ||
-      viewport_style->OverflowY() != overflow_y ||
-      viewport_style->ColumnGap() != column_gap ||
-      viewport_style->GetScrollSnapType() != snap_type ||
-      viewport_style->GetScrollBehavior() != scroll_behavior ||
-      viewport_style->OverscrollBehaviorX() != overscroll_behavior_x ||
-      viewport_style->OverscrollBehaviorY() != overscroll_behavior_y ||
-      viewport_style->ScrollPaddingTop() != scroll_padding_top ||
-      viewport_style->ScrollPaddingRight() != scroll_padding_right ||
-      viewport_style->ScrollPaddingBottom() != scroll_padding_bottom ||
-      viewport_style->ScrollPaddingLeft() != scroll_padding_left) {
+      viewport_style.BackgroundLayers() != background_layers ||
+      viewport_style.ImageRendering() != image_rendering ||
+      viewport_style.OverflowAnchor() != overflow_anchor ||
+      viewport_style.OverflowX() != overflow_x ||
+      viewport_style.OverflowY() != overflow_y ||
+      viewport_style.ColumnGap() != column_gap ||
+      viewport_style.GetScrollSnapType() != snap_type ||
+      viewport_style.GetScrollBehavior() != scroll_behavior ||
+      viewport_style.OverscrollBehaviorX() != overscroll_behavior_x ||
+      viewport_style.OverscrollBehaviorY() != overscroll_behavior_y ||
+      viewport_style.ScrollPaddingTop() != scroll_padding_top ||
+      viewport_style.ScrollPaddingRight() != scroll_padding_right ||
+      viewport_style.ScrollPaddingBottom() != scroll_padding_bottom ||
+      viewport_style.ScrollPaddingLeft() != scroll_padding_left) {
     scoped_refptr<ComputedStyle> new_style =
-        ComputedStyle::Clone(*viewport_style);
+        ComputedStyle::Clone(viewport_style);
     new_style->SetWritingMode(root_writing_mode);
     new_style->SetDirection(root_direction);
     new_style->SetBackgroundColor(background_color);

diff --git a/third_party/WebKit/Source/core/layout/LayoutBlock.cpp b/third_party/WebKit/Source/core/layout/LayoutBlock.cpp
index 9d59498..39b1fb4 100644
--- a/third_party/WebKit/Source/core/layout/LayoutBlock.cpp
+++ b/third_party/WebKit/Source/core/layout/LayoutBlock.cpp

@@ -1465,17 +1465,17 @@
       child->SetPreferredLogicalWidthsDirty();
     }
 
-    scoped_refptr<ComputedStyle> child_style = child->MutableStyle();
+    const ComputedStyle& child_style = child->StyleRef();
     if (child->IsFloating() ||
         (child->IsBox() && ToLayoutBox(child)->AvoidsFloats())) {
       LayoutUnit float_total_width = float_left_width + float_right_width;
-      if (child_style->Clear() == EClear::kBoth ||
-          child_style->Clear() == EClear::kLeft) {
+      if (child_style.Clear() == EClear::kBoth ||
+          child_style.Clear() == EClear::kLeft) {
         max_logical_width = std::max(float_total_width, max_logical_width);
         float_left_width = LayoutUnit();
       }
-      if (child_style->Clear() == EClear::kBoth ||
-          child_style->Clear() == EClear::kRight) {
+      if (child_style.Clear() == EClear::kBoth ||
+          child_style.Clear() == EClear::kRight) {
         max_logical_width = std::max(float_total_width, max_logical_width);
         float_right_width = LayoutUnit();
       }
@@ -1485,8 +1485,8 @@
     // (variable).
     // Auto and percentage margins simply become 0 when computing min/max width.
     // Fixed margins can be added in as is.
-    Length start_margin_length = child_style->MarginStartUsing(style_to_use);
-    Length end_margin_length = child_style->MarginEndUsing(style_to_use);
+    Length start_margin_length = child_style.MarginStartUsing(style_to_use);
+    Length end_margin_length = child_style.MarginEndUsing(style_to_use);
     LayoutUnit margin;
     LayoutUnit margin_start;
     LayoutUnit margin_end;
@@ -1540,7 +1540,7 @@
     }
 
     if (child->IsFloating()) {
-      if (child_style->Floating() == EFloat::kLeft)
+      if (child_style.Floating() == EFloat::kLeft)
         float_left_width += w;
       else
         float_right_width += w;