Remove non-impl-side painting as an option for blink.

content/public/common/content_switches.cc

Index: content/public/common/content_switches.cc
diff --git a/content/public/common/content_switches.cc b/content/public/common/content_switches.cc
index d383ef472d481e0a40571e36cd77d0159849a202..7878384d4db7bd36714733ff4dbe8aa21433ddc1 100644
--- a/content/public/common/content_switches.cc
+++ b/content/public/common/content_switches.cc
@@ -161,9 +161,6 @@ const char kDisableHideInactiveStackedTabCloseButtons[] =
 // Disable the RenderThread's HistogramCustomizer.
 const char kDisableHistogramCustomizer[]    = "disable-histogram-customizer";
 
-// Paint content on the main thread instead of the compositor thread.
-const char kDisableImplSidePainting[]       = "disable-impl-side-painting";
-
 // Prevent Java from running.
 const char kDisableJava[]                   = "disable-java";
 
@@ -316,9 +313,6 @@ const char kEnableBlinkFeatures[]           = "enable-blink-features";
 // PlzNavigate: Use the experimental browser-side navigation path.
 const char kEnableBrowserSideNavigation[]   = "enable-browser-side-navigation";
 
-// Defer image decoding in WebKit until painting.
-const char kEnableDeferredImageDecoding[]   = "enable-deferred-image-decoding";
-
 // Enables Delay Agnostic AEC in WebRTC.
 const char kEnableDelayAgnosticAec[]        = "enable-delay-agnostic-aec";