Enable stencil clipping in mixed sampled render targets

src/gpu/gl/GrGLCaps.cpp

Index: src/gpu/gl/GrGLCaps.cpp
diff --git a/src/gpu/gl/GrGLCaps.cpp b/src/gpu/gl/GrGLCaps.cpp
index 6522e1b14bce63256dd822c3ecb973934c50d1e5..8101b82ae46784eb9610855a9dc24c9a7bb21332 100644
--- a/src/gpu/gl/GrGLCaps.cpp
+++ b/src/gpu/gl/GrGLCaps.cpp
@@ -348,7 +348,8 @@ void GrGLCaps::init(const GrContextOptions& contextOptions,
         glslCaps->fMixedSamplesSupport =
             ctxInfo.hasExtension("GL_NV_framebuffer_mixed_samples") &&
             ctxInfo.hasExtension("GL_NV_sample_mask_override_coverage") &&
-            ctxInfo.hasExtension("GL_EXT_raster_multisample");
+            ctxInfo.hasExtension("GL_EXT_raster_multisample") &&
+            ctxInfo.hasExtension("GL_NV_sample_locations");

[Chris Dalton, 2015/09/22 08:35:24]

With our current plans to just put basic mixed samples support in the chromium
command buffer, it won't work to rope this extension in with mixed samples as
well. I'm afraid we're going to have to make a separate cap for sample
locations, and then check that specific cap before trying to use an MSAA stencil
clip.

     }
     // Workaround NVIDIA bug related to glInvalidateFramebuffer and mixed samples.
     if (kNVIDIA_GrGLDriver == ctxInfo.driver() && fShaderCaps->mixedSamplesSupport()) {