Add support for GL_EXT_raster_multisample

include/gpu/GrCaps.h

Index: include/gpu/GrCaps.h
diff --git a/include/gpu/GrCaps.h b/include/gpu/GrCaps.h
index 05da8d7cadf40d5af5eafa185b03ad761c8b7029..248298e01a1325772df631f94b7b646e4b2f174e 100644
--- a/include/gpu/GrCaps.h
+++ b/include/gpu/GrCaps.h
@@ -143,6 +143,9 @@ public:
     bool oversizedStencilSupport() const { return fOversizedStencilSupport; }
     bool textureBarrierSupport() const { return fTextureBarrierSupport; }
     bool usesMixedSamples() const { return fUsesMixedSamples; }
+    /** "Raster multisample" is a special HW mode where the rasterizer runs more samples than are in
+        the target framebuffer. */
+    bool rasterMultisampleSupport() const { return fRasterMultisampleSupport; }
 
     bool useDrawInsteadOfClear() const { return fUseDrawInsteadOfClear; }
     bool useDrawInsteadOfPartialRenderTargetWrite() const {
@@ -220,6 +223,11 @@ public:
             return SkTMin(this->maxColorSampleCount(), this->maxStencilSampleCount());
         }
     }
+    // This can only be called if raster multisample is supported.
+    int maxRasterSamples() const {
+        SkASSERT(this->rasterMultisampleSupport());
+        return fMaxRasterSamples;
+    }
 
 
     virtual bool isConfigTexturable(GrPixelConfig config) const = 0;
@@ -268,6 +276,7 @@ protected:
     bool fOversizedStencilSupport                    : 1;
     bool fTextureBarrierSupport                      : 1;
     bool fUsesMixedSamples                           : 1;
+    bool fRasterMultisampleSupport                   : 1;
     bool fSupportsInstancedDraws                     : 1;
     bool fFullClearIsFree                            : 1;
     bool fMustClearUploadedBufferData                : 1;
@@ -291,6 +300,7 @@ protected:
     int fMaxTileSize;
     int fMaxColorSampleCount;
     int fMaxStencilSampleCount;
+    int fMaxRasterSamples;
 
 private:
     virtual void onApplyOptionsOverrides(const GrContextOptions&) {};