Make ComputedStyle::SetFontDescription() preserve FontSelector value

ComputedStyle::SetFontDescription() clears the FontFallbackList (and
hence, FontSelector) on the Font object when successful. As a result,
callers, need to store the FontSelector value before calling, and use
Update() to restore it after calling.

This patch makes SetFontDescription() preserve the FontSelector value,
so that the pattern can be eliminated, and we have fewer call sites of
the deprecated function Font::Update().

Bug: 1049295
Change-Id: I6f4c17d3d0cfe79d2f32ca610ad39ecbf75e2d54
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2108867Reviewed-by: Rune Lillesveen <futhark@chromium.org>
Commit-Queue: Xiaocheng Hu <xiaochengh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#751545}

third_party/blink/renderer/core/layout/layout_text_combine.cc

@@ -177,7 +177,7 @@ void LayoutTextCombine::UpdateFontStyleForCombinedText() {
   FontSelector* font_selector = style->GetFont().GetFontSelector();
 
   // Need to change font orientation to horizontal.
-  bool should_update_font = style->SetFontDescription(description);
+  style->SetFontDescription(description);
 
   if (combined_text_width_ <= em_width) {
     scale_x_ = 1.0f;
@@ -193,7 +193,7 @@ void LayoutTextCombine::UpdateFontStyleForCombinedText() {
         combined_text_width_ = run_width;
 
         // Replace my font with the new one.
-        should_update_font = style->SetFontDescription(description);
+        style->SetFontDescription(description);
         break;
       }
     }
@@ -208,9 +208,6 @@ void LayoutTextCombine::UpdateFontStyleForCombinedText() {
       scale_x_ = 1.0f;
     }
   }
-
-  if (should_update_font)
-    style->GetFont().Update(font_selector);
 }
 
 }  // namespace blink

third_party/blink/renderer/core/layout/layout_theme_mac.mm

@@ -715,10 +715,7 @@ void LayoutThemeMac::SetFontFromControlSize(ComputedStyle& style,
   // Reset line height.
   style.SetLineHeight(ComputedStyleInitialValues::InitialLineHeight());
 
-  // TODO(esprehn): The fontSelector manual management is buggy and error prone.
-  FontSelector* font_selector = style.GetFont().GetFontSelector();
-  if (style.SetFontDescription(font_description))
-    style.GetFont().Update(font_selector);
+  style.SetFontDescription(font_description);
 }
 
 NSControlSize LayoutThemeMac::ControlSizeForSystemFont(

third_party/blink/renderer/core/style/computed_style.cc

@@ -1779,11 +1779,9 @@ void ComputedStyle::UpdateFontOrientation() {
   FontOrientation orientation = ComputeFontOrientation();
   if (GetFontDescription().Orientation() == orientation)
     return;
-  FontSelector* current_font_selector = GetFont().GetFontSelector();
   FontDescription font_description = GetFontDescription();
   font_description.SetOrientation(orientation);
   SetFontDescription(font_description);
-  GetFont().Update(current_font_selector);
 }
 
 TextDecoration ComputedStyle::TextDecorationsInEffect() const {
@@ -1959,7 +1957,7 @@ const CSSValue* ComputedStyle::GetVariableValue(
 
 bool ComputedStyle::SetFontDescription(const FontDescription& v) {
   if (FontInternal().GetFontDescription() != v) {
-    SetFontInternal(Font(v));
+    SetFontInternal(Font(v, FontInternal().GetFontSelector()));
     return true;
   }
   return false;
@@ -2020,19 +2018,15 @@ LayoutUnit ComputedStyle::ComputedLineHeightAsFixed() const {
 }
 
 void ComputedStyle::SetWordSpacing(float word_spacing) {
-  FontSelector* current_font_selector = GetFont().GetFontSelector();
   FontDescription desc(GetFontDescription());
   desc.SetWordSpacing(word_spacing);
   SetFontDescription(desc);
-  GetFont().Update(current_font_selector);
 }
 
 void ComputedStyle::SetLetterSpacing(float letter_spacing) {
-  FontSelector* current_font_selector = GetFont().GetFontSelector();
   FontDescription desc(GetFontDescription());
   desc.SetLetterSpacing(letter_spacing);
   SetFontDescription(desc);
-  GetFont().Update(current_font_selector);
 }
 
 void ComputedStyle::SetTextAutosizingMultiplier(float multiplier) {
@@ -2046,7 +2040,6 @@ void ComputedStyle::SetTextAutosizingMultiplier(float multiplier) {
   else
     size = std::min(kMaximumAllowedFontSize, size);
 
-  FontSelector* current_font_selector = GetFont().GetFontSelector();
   FontDescription desc(GetFontDescription());
   desc.SetSpecifiedSize(size);
 
@@ -2057,7 +2050,6 @@ void ComputedStyle::SetTextAutosizingMultiplier(float multiplier) {
   desc.SetComputedSize(std::min(kMaximumAllowedFontSize, autosized_font_size));
 
   SetFontDescription(desc);
-  GetFont().Update(current_font_selector);
 }
 
 void ComputedStyle::AddAppliedTextDecoration(