Make max number of vertex attributes be checked dynamically

src/gpu/GrPrimitiveProcessor.h

Index: src/gpu/GrPrimitiveProcessor.h
diff --git a/src/gpu/GrPrimitiveProcessor.h b/src/gpu/GrPrimitiveProcessor.h
index e5c8517250cec51790a50b85a087f75a6db483b5..e8bb449888460c33dce1cbeb07f5cf7e570eeb15 100644
--- a/src/gpu/GrPrimitiveProcessor.h
+++ b/src/gpu/GrPrimitiveProcessor.h
@@ -151,12 +151,6 @@ public:
     // we put these calls on the base class to prevent having to cast
     virtual bool willUseGeoShader() const = 0;
 
-    /*
-     * This is a safeguard to prevent GrPrimitiveProcessor's from going beyond platform specific
-     * attribute limits. This number can almost certainly be raised if required.
-     */
-    static const int kMaxVertexAttribs = 8;
-
     struct Attribute {
         Attribute()
             : fName(nullptr)
@@ -174,11 +168,8 @@ public:
         GrSLPrecision fPrecision;
     };
 
-    int numAttribs() const { return fNumAttribs; }
-    const Attribute& getAttrib(int index) const {
-        SkASSERT(index < fNumAttribs);
-        return fAttribs[index];
-    }
+    int numAttribs() const { return fAttribs.count(); }
+    const Attribute& getAttrib(int index) const { return fAttribs[index]; }
 
     // Returns the vertex stride of the GP.  A common use case is to request geometry from a
     // drawtarget based off of the stride, and to populate this memory using an implicit array of
@@ -227,12 +218,10 @@ public:
     virtual const char* getDestColorOverride() const { return nullptr; }
     
 protected:
-    GrPrimitiveProcessor()
-        : fNumAttribs(0)
-        , fVertexStride(0) {}
+    GrPrimitiveProcessor() : fVertexStride(0) {}
 
-    Attribute fAttribs[kMaxVertexAttribs];
-    int fNumAttribs;
+    enum { kPreallocAttribCnt = 8 };
+    SkSTArray<kPreallocAttribCnt, Attribute> fAttribs;
     size_t fVertexStride;
 
 private: