From 4c41f32a2751c975ede6056627c8281dd4cf5c30 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Emilio=20Cobos=20=C3=81lvarez?= <emilio@crisal.io>
Date: Tue, 25 Jan 2022 21:31:43 +0000
Subject: [PATCH] Bug 1749531 - Manage native theme lifetime from Theme.cpp.
 r=mstange

Differential Revision: https://phabricator.services.mozilla.com/D136127
---
 gfx/src/nsITheme.h                  |  7 ++++++
 widget/Theme.cpp                    | 38 +++++++++++++++++------------
 widget/cocoa/nsNativeThemeCocoa.mm  | 11 ++-------
 widget/gtk/nsNativeThemeGTK.cpp     | 16 +++---------
 widget/windows/nsNativeThemeWin.cpp | 11 ++-------
 5 files changed, 38 insertions(+), 45 deletions(-)

diff --git a/gfx/src/nsITheme.h b/gfx/src/nsITheme.h
index 52e36504615c..8384f0f728a3 100644
--- a/gfx/src/nsITheme.h
+++ b/gfx/src/nsITheme.h
@@ -32,6 +32,9 @@ namespace layers {
 class StackingContextHelper;
 class RenderRootStateManager;
 }  // namespace layers
+namespace widget {
+class Theme;
+}  // namespace widget
 namespace wr {
 class DisplayListBuilder;
 class IpcResourceUpdateQueue;
@@ -268,4 +271,8 @@ extern already_AddRefed<nsITheme> do_GetNativeThemeDoNotUseDirectly();
 extern already_AddRefed<nsITheme> do_GetBasicNativeThemeDoNotUseDirectly();
 extern already_AddRefed<nsITheme> do_GetRDMThemeDoNotUseDirectly();
 
+// Native theme creation function, these should never return null.
+extern already_AddRefed<mozilla::widget::Theme>
+do_CreateNativeThemeDoNotUseDirectly();
+
 #endif
diff --git a/widget/Theme.cpp b/widget/Theme.cpp
index 360ff75d1dd3..fc4bb724e91e 100644
--- a/widget/Theme.cpp
+++ b/widget/Theme.cpp
@@ -107,30 +107,39 @@ struct MOZ_RAII AutoClipRect {
   DrawTarget& mDt;
 };
 
-static StaticRefPtr<nsITheme> gInstance;
-static StaticRefPtr<nsITheme> gRDMInstance;
+static StaticRefPtr<Theme> gNativeInstance;
+static StaticRefPtr<Theme> gNonNativeInstance;
+static StaticRefPtr<Theme> gRDMInstance;
 
 }  // namespace
 
+#ifdef ANDROID
+already_AddRefed<Theme> do_CreateNativeThemeDoNotUseDirectly() {
+  // Android doesn't have a native theme.
+  return do_AddRef(new Theme(Theme::ScrollbarStyle()));
+}
+#endif
+
 already_AddRefed<nsITheme> do_GetBasicNativeThemeDoNotUseDirectly() {
-  if (MOZ_UNLIKELY(!gInstance)) {
+  if (MOZ_UNLIKELY(!gNonNativeInstance)) {
     UniquePtr<ScrollbarDrawing> scrollbarDrawing = Theme::ScrollbarStyle();
 #ifdef MOZ_WIDGET_COCOA
-    gInstance = new ThemeCocoa(std::move(scrollbarDrawing));
+    gNonNativeInstance = new ThemeCocoa(std::move(scrollbarDrawing));
 #else
-    gInstance = new Theme(std::move(scrollbarDrawing));
+    gNonNativeInstance = new Theme(std::move(scrollbarDrawing));
 #endif
-    ClearOnShutdown(&gInstance);
+    ClearOnShutdown(&gNonNativeInstance);
   }
-  return do_AddRef(gInstance);
+  return do_AddRef(gNonNativeInstance);
 }
 
-#ifdef ANDROID
 already_AddRefed<nsITheme> do_GetNativeThemeDoNotUseDirectly() {
-  // Android doesn't have a native theme.
-  return do_GetBasicNativeThemeDoNotUseDirectly();
+  if (MOZ_UNLIKELY(!gNativeInstance)) {
+    gNativeInstance = do_CreateNativeThemeDoNotUseDirectly();
+    ClearOnShutdown(&gNativeInstance);
+  }
+  return do_AddRef(gNativeInstance);
 }
-#endif
 
 already_AddRefed<nsITheme> do_GetRDMThemeDoNotUseDirectly() {
   if (MOZ_UNLIKELY(!gRDMInstance)) {
@@ -167,10 +176,9 @@ void Theme::Shutdown() {
 /* static */
 void Theme::LookAndFeelChanged() {
   ThemeColors::RecomputeAccentColors();
-  auto* basicTheme = static_cast<Theme*>(gInstance.get());
-  if (basicTheme) {
-    basicTheme->SetScrollbarDrawing(Theme::ScrollbarStyle());
-    basicTheme->GetScrollbarDrawing().RecomputeScrollbarParams();
+  if (gNonNativeInstance) {
+    gNonNativeInstance->SetScrollbarDrawing(Theme::ScrollbarStyle());
+    gNonNativeInstance->GetScrollbarDrawing().RecomputeScrollbarParams();
   }
 }
 
diff --git a/widget/cocoa/nsNativeThemeCocoa.mm b/widget/cocoa/nsNativeThemeCocoa.mm
index 5c2875079d05..78592df24b0e 100644
--- a/widget/cocoa/nsNativeThemeCocoa.mm
+++ b/widget/cocoa/nsNativeThemeCocoa.mm
@@ -3644,13 +3644,6 @@ nsITheme::Transparency nsNativeThemeCocoa::GetWidgetTransparency(nsIFrame* aFram
   }
 }
 
-already_AddRefed<nsITheme> do_GetNativeThemeDoNotUseDirectly() {
-  static nsCOMPtr<nsITheme> inst;
-
-  if (!inst) {
-    inst = new nsNativeThemeCocoa(MakeUnique<ScrollbarDrawingCocoa>());
-    ClearOnShutdown(&inst);
-  }
-
-  return do_AddRef(inst);
+already_AddRefed<widget::Theme> do_CreateNativeThemeDoNotUseDirectly() {
+  return do_AddRef(new nsNativeThemeCocoa(MakeUnique<ScrollbarDrawingCocoa>()));
 }
diff --git a/widget/gtk/nsNativeThemeGTK.cpp b/widget/gtk/nsNativeThemeGTK.cpp
index eb9560459e1c..11df4735b60e 100644
--- a/widget/gtk/nsNativeThemeGTK.cpp
+++ b/widget/gtk/nsNativeThemeGTK.cpp
@@ -1668,17 +1668,9 @@ nsITheme::Transparency nsNativeThemeGTK::GetWidgetTransparency(
   }
 }
 
-already_AddRefed<nsITheme> do_GetNativeThemeDoNotUseDirectly() {
-  static nsCOMPtr<nsITheme> inst;
-
-  if (!inst) {
-    if (gfxPlatform::IsHeadless()) {
-      inst = new Theme(Theme::DefaultPlatformScrollbarStyle());
-    } else {
-      inst = new nsNativeThemeGTK();
-    }
-    ClearOnShutdown(&inst);
+already_AddRefed<Theme> do_CreateNativeThemeDoNotUseDirectly() {
+  if (gfxPlatform::IsHeadless()) {
+    return do_AddRef(new Theme(Theme::DefaultPlatformScrollbarStyle()));
   }
-
-  return do_AddRef(inst);
+  return do_AddRef(new nsNativeThemeGTK());
 }
diff --git a/widget/windows/nsNativeThemeWin.cpp b/widget/windows/nsNativeThemeWin.cpp
index e7dd23ac511c..7f34447c0278 100644
--- a/widget/windows/nsNativeThemeWin.cpp
+++ b/widget/windows/nsNativeThemeWin.cpp
@@ -3662,13 +3662,6 @@ uint32_t nsNativeThemeWin::GetWidgetNativeDrawingFlags(
 // Creation Routine
 ///////////////////////////////////////////
 
-already_AddRefed<nsITheme> do_GetNativeThemeDoNotUseDirectly() {
-  static nsCOMPtr<nsITheme> inst;
-
-  if (!inst) {
-    inst = new nsNativeThemeWin();
-    ClearOnShutdown(&inst);
-  }
-
-  return do_AddRef(inst);
+already_AddRefed<Theme> do_CreateNativeThemeDoNotUseDirectly() {
+  return do_AddRef(new nsNativeThemeWin());
 }