Combine ComputedStyle default ctor with initial style ctor.

third_party/WebKit/Source/core/style/ComputedStyle.cpp

Index: third_party/WebKit/Source/core/style/ComputedStyle.cpp
diff --git a/third_party/WebKit/Source/core/style/ComputedStyle.cpp b/third_party/WebKit/Source/core/style/ComputedStyle.cpp
index e4f24e005bee513d9a4e1a402542a26e95300fbe..5f794c720cc137fe6b502374eaf22954a2bc26d8 100644
--- a/third_party/WebKit/Source/core/style/ComputedStyle.cpp
+++ b/third_party/WebKit/Source/core/style/ComputedStyle.cpp
@@ -95,7 +95,7 @@ struct SameSizeAsComputedStyle : public RefCounted<SameSizeAsComputedStyle> {
 ASSERT_SIZE(ComputedStyle, SameSizeAsComputedStyle);
 
 PassRefPtr<ComputedStyle> ComputedStyle::create() {
-  return adoptRef(new ComputedStyle());

[sashab, 2017/03/09 23:48:22]

Does this have a perf cost?

[shend, 2017/03/14 06:05:21]

Shouldn't affect perf since initialStyle() returns a cached initial style.

+  return adoptRef(new ComputedStyle(initialStyle()));
 }
 
 PassRefPtr<ComputedStyle> ComputedStyle::createInitialStyle() {
@@ -120,24 +120,6 @@ PassRefPtr<ComputedStyle> ComputedStyle::clone(const ComputedStyle& other) {
   return adoptRef(new ComputedStyle(other));
 }
 
-ALWAYS_INLINE ComputedStyle::ComputedStyle()
-    : ComputedStyleBase(),
-      RefCounted<ComputedStyle>(),
-      m_box(initialStyle().m_box),
-      m_visual(initialStyle().m_visual),
-      m_background(initialStyle().m_background),
-      m_surround(initialStyle().m_surround),
-      m_rareNonInheritedData(initialStyle().m_rareNonInheritedData),
-      m_rareInheritedData(initialStyle().m_rareInheritedData),
-      m_styleInheritedData(initialStyle().m_styleInheritedData),
-      m_svgStyle(initialStyle().m_svgStyle) {
-  initializeBitDefaults();  // Would it be faster to copy this from the default
-                            // style?
-  static_assert((sizeof(InheritedData) <= 8), "InheritedData should not grow");
-  static_assert((sizeof(NonInheritedData) <= 12),
-                "NonInheritedData should not grow");
-}
-
 ALWAYS_INLINE ComputedStyle::ComputedStyle(InitialStyleTag)
     : ComputedStyleBase(), RefCounted<ComputedStyle>() {
   initializeBitDefaults();
@@ -160,6 +142,10 @@ ALWAYS_INLINE ComputedStyle::ComputedStyle(InitialStyleTag)
   m_rareInheritedData.init();
   m_styleInheritedData.init();
   m_svgStyle.init();
+
+  static_assert((sizeof(InheritedData) <= 8), "InheritedData should not grow");
+  static_assert((sizeof(NonInheritedData) <= 12),
+                "NonInheritedData should not grow");

[meade_UTC10, 2017/03/09 05:43:13]

Is there a problem with moving these static_asserts to the other constructor?
I'm a bit confused about why they are here in the first place. We semm to use
that SameSizeAsFoo idiom elsewhere - perhaps that is more appropriate here?
Sasha might have a stronger opinion than me...

[shend, 2017/03/09 14:59:54]

Yeah I don't know why they're in the constructor. In ComputedStyleBase, we put
them after the SameAsSize struct. I can move them to be consistent with
ComputedStyleBase.

[sashab, 2017/03/09 23:48:22]

Hmm, you can check git blame, but this looks like an artifact left over from
before we had the SameSizeAs structs.

You can actually just delete these altogether - since ComputedStyle is going
away, anything added will be added to ComputedStyleBase, which has its own size
check.

[shend, 2017/03/14 06:05:21]

Done.

 }
 
 ALWAYS_INLINE ComputedStyle::ComputedStyle(const ComputedStyle& o)