From 0acba278661e891d32a9c094c091b3f179296f22 Mon Sep 17 00:00:00 2001
From: Lee Salzman <lsalzman@mozilla.com>
Date: Mon, 24 Jun 2019 18:45:16 +0000
Subject: [PATCH] Bug 1559810 - disallow Cairo as content/canvas backend.
 r=jrmuizel

Differential Revision: https://phabricator.services.mozilla.com/D35691

--HG--
extra : moz-landing-system : lando
---
 gfx/thebes/gfxPlatform.cpp        | 22 +++++++++++++---------
 gfx/thebes/gfxWindowsPlatform.cpp |  6 ++----
 modules/libpref/init/all.js       |  6 +++---
 3 files changed, 18 insertions(+), 16 deletions(-)

diff --git a/gfx/thebes/gfxPlatform.cpp b/gfx/thebes/gfxPlatform.cpp
index 55f6f8ab49c6..3ed920e442b1 100644
--- a/gfx/thebes/gfxPlatform.cpp
+++ b/gfx/thebes/gfxPlatform.cpp
@@ -1875,14 +1875,16 @@ mozilla::layers::DiagnosticTypes gfxPlatform::GetLayerDiagnosticTypes() {
 BackendPrefsData gfxPlatform::GetBackendPrefs() const {
   BackendPrefsData data;
 
-  data.mCanvasBitmask = BackendTypeBit(BackendType::CAIRO);
-  data.mContentBitmask = BackendTypeBit(BackendType::CAIRO);
-#ifdef USE_SKIA
-  data.mCanvasBitmask |= BackendTypeBit(BackendType::SKIA);
-  data.mContentBitmask |= BackendTypeBit(BackendType::SKIA);
+  data.mCanvasBitmask = BackendTypeBit(BackendType::SKIA);
+  data.mContentBitmask = BackendTypeBit(BackendType::SKIA);
+
+#ifdef MOZ_WIDGET_GTK
+  data.mCanvasBitmask |= BackendTypeBit(BackendType::CAIRO);
+  data.mContentBitmask |= BackendTypeBit(BackendType::CAIRO);
 #endif
-  data.mCanvasDefault = BackendType::CAIRO;
-  data.mContentDefault = BackendType::CAIRO;
+
+  data.mCanvasDefault = BackendType::SKIA;
+  data.mContentDefault = BackendType::SKIA;
 
   return data;
 }
@@ -1915,8 +1917,10 @@ void gfxPlatform::InitBackendPrefs(BackendPrefsData&& aPrefsData) {
     mContentBackendBitmask |= BackendTypeBit(aPrefsData.mContentDefault);
   }
 
-  uint32_t swBackendBits =
-      BackendTypeBit(BackendType::SKIA) | BackendTypeBit(BackendType::CAIRO);
+  uint32_t swBackendBits = BackendTypeBit(BackendType::SKIA);
+#ifdef MOZ_WIDGET_GTK
+  swBackendBits |= BackendTypeBit(BackendType::CAIRO);
+#endif
   mSoftwareBackend = GetContentBackendPref(swBackendBits);
 
   if (XRE_IsParentProcess()) {
diff --git a/gfx/thebes/gfxWindowsPlatform.cpp b/gfx/thebes/gfxWindowsPlatform.cpp
index 748bc35434d5..250ce20cb263 100644
--- a/gfx/thebes/gfxWindowsPlatform.cpp
+++ b/gfx/thebes/gfxWindowsPlatform.cpp
@@ -516,10 +516,8 @@ bool gfxWindowsPlatform::HandleDeviceReset() {
 BackendPrefsData gfxWindowsPlatform::GetBackendPrefs() const {
   BackendPrefsData data;
 
-  data.mCanvasBitmask =
-      BackendTypeBit(BackendType::CAIRO) | BackendTypeBit(BackendType::SKIA);
-  data.mContentBitmask =
-      BackendTypeBit(BackendType::CAIRO) | BackendTypeBit(BackendType::SKIA);
+  data.mCanvasBitmask = BackendTypeBit(BackendType::SKIA);
+  data.mContentBitmask = BackendTypeBit(BackendType::SKIA);
   data.mCanvasDefault = BackendType::SKIA;
   data.mContentDefault = BackendType::SKIA;
 
diff --git a/modules/libpref/init/all.js b/modules/libpref/init/all.js
index 142dd410fa88..e33e66179edf 100644
--- a/modules/libpref/init/all.js
+++ b/modules/libpref/init/all.js
@@ -765,9 +765,9 @@ pref("gfx.font_ahem_antialias_none", false);
 
 #ifdef XP_WIN
 // comma separated list of backends to use in order of preference
-// e.g., pref("gfx.canvas.azure.backends", "direct2d,skia,cairo");
-pref("gfx.canvas.azure.backends", "direct2d1.1,skia,cairo");
-pref("gfx.content.azure.backends", "direct2d1.1,skia,cairo");
+// e.g., pref("gfx.canvas.azure.backends", "direct2d,skia");
+pref("gfx.canvas.azure.backends", "direct2d1.1,skia");
+pref("gfx.content.azure.backends", "direct2d1.1,skia");
 pref("gfx.canvas.remote", false);
 #else
 #ifdef XP_MACOSX