Allow GrGLEffects to produce variable length keys.

R=robertphillips@google.com, jvanverth@google.com

Author: bsalomon@google.com

Review URL: https://codereview.chromium.org/385713005
diff --git a/src/gpu/GrAARectRenderer.cpp b/src/gpu/GrAARectRenderer.cpp
index 761c63f..59e9b6f 100644
--- a/src/gpu/GrAARectRenderer.cpp
+++ b/src/gpu/GrAARectRenderer.cpp
@@ -46,7 +46,7 @@
 
         virtual void emitCode(GrGLFullShaderBuilder* builder,
                               const GrDrawEffect& drawEffect,
-                              EffectKey key,
+                              const GrEffectKey& key,
                               const char* outputColor,
                               const char* inputColor,
                               const TransformedCoordsArray&,
@@ -88,9 +88,7 @@
                                    (GrGLSLExpr4(inputColor) * GrGLSLExpr1("coverage")).c_str());
         }
 
-        static inline EffectKey GenKey(const GrDrawEffect& drawEffect, const GrGLCaps&) {
-            return 0;
-        }
+        static void GenKey(const GrDrawEffect&, const GrGLCaps&, GrEffectKeyBuilder*) {}
 
         virtual void setData(const GrGLUniformManager& uman, const GrDrawEffect&) SK_OVERRIDE {}
 
@@ -164,7 +162,7 @@
 
         virtual void emitCode(GrGLFullShaderBuilder* builder,
                               const GrDrawEffect& drawEffect,
-                              EffectKey key,
+                              const GrEffectKey& key,
                               const char* outputColor,
                               const char* inputColor,
                               const TransformedCoordsArray&,
@@ -221,9 +219,7 @@
                                    (GrGLSLExpr4(inputColor) * GrGLSLExpr1("coverage")).c_str());
         }
 
-        static inline EffectKey GenKey(const GrDrawEffect& drawEffect, const GrGLCaps&) {
-            return 0;
-        }
+        static void GenKey(const GrDrawEffect&, const GrGLCaps&, GrEffectKeyBuilder*) {}
 
         virtual void setData(const GrGLUniformManager& uman, const GrDrawEffect&) SK_OVERRIDE {}