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

content/test/fake_compositor_dependencies.cc

Index: content/test/fake_compositor_dependencies.cc
diff --git a/content/test/fake_compositor_dependencies.cc b/content/test/fake_compositor_dependencies.cc
index 37ef965dc6364f749971b23a947a2b598145aa89..e33554d969e5c27aec76f33ff8e3f21e29bb7e2d 100644
--- a/content/test/fake_compositor_dependencies.cc
+++ b/content/test/fake_compositor_dependencies.cc
@@ -17,10 +17,6 @@ FakeCompositorDependencies::FakeCompositorDependencies() {
 FakeCompositorDependencies::~FakeCompositorDependencies() {
 }
 
-bool FakeCompositorDependencies::IsImplSidePaintingEnabled() {
-  return true;
-}
-
 bool FakeCompositorDependencies::IsGpuRasterizationForced() {
   return false;
 }