Revert of Makes GrGLProgramDesc's key store the lengths as well as offsets of the effect keys.

include/gpu/GrTBackendEffectFactory.h

 /*
  * Copyright 2012 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef GrTBackendEffectFactory_DEFINED
 #define GrTBackendEffectFactory_DEFINED
 
 #include "GrBackendEffectFactory.h"
 #include "GrDrawEffect.h"
 #include "gl/GrGLProgramEffects.h"
 
 /**
- * Implements GrBackendEffectFactory for a GrEffect subclass as a singleton. This can be used by
- * most GrEffect subclasses to implement the GrEffect::getFactory() method:
- *
- * const GrBackendEffectFactory& MyEffect::getFactory() const {
- *     return GrTBackendEffectFactory<MyEffect>::getInstance();
- * }
- *
- * Using this class requires that the GrEffect subclass always produces the same GrGLEffect
- * subclass. Additionally, It adds the following requirements to the GrEffect and GrGLEffect
- * subclasses:
- *
- * 1. The GrGLEffect used by GrEffect subclass MyEffect must be named or typedef'ed to
- *    MyEffect::GLEffect.
- * 2. MyEffect::GLEffect must have a static function:
- *      EffectKey GenKey(const GrDrawEffect, const GrGLCaps&)
- *    which generates a key that maps 1 to 1 with code variations emitted by
- *    MyEffect::GLEffect::emitCode().
- * 3. MyEffect must have a static function:
- *      const char* Name()
- *    which returns a human-readable name for the effect.
+ * Implements GrBackendEffectFactory for a GrEffect subclass as a singleton.
  */
 template <typename EffectClass>
 class GrTBackendEffectFactory : public GrBackendEffectFactory {
 
 public:
     typedef typename EffectClass::GLEffect GLEffect;
 
-    /** Returns a human-readable name for the effect. Implemented using GLEffect::Name as described
-     *  in this class's comment. */
+    /** Returns a human-readable name that is accessible via GrEffect or
+        GrGLEffect and is consistent between the two of them.
+     */
     virtual const char* name() const SK_OVERRIDE { return EffectClass::Name(); }
 
-
-    /** Implemented using GLEffect::GenKey as described in this class's comment. */
-    virtual void getGLEffectKey(const GrDrawEffect& drawEffect,
+    /** Generates an effect's key. This enables caching of generated shaders. Part of the
+        id identifies the GrEffect subclass. The remainder is based on the aspects of the
+        GrEffect object's configuration that affect GLSL code generation. If this fails
+        then program generation should be aborted. Failure occurs if the effect uses more
+        transforms, attributes, or textures than the key has space for. */
+    virtual bool getGLEffectKey(const GrDrawEffect& drawEffect,
                                 const GrGLCaps& caps,
                                 GrEffectKeyBuilder* b) const SK_OVERRIDE {
+        SkASSERT(kIllegalEffectClassID != fEffectClassID);
         EffectKey effectKey = GLEffect::GenKey(drawEffect, caps);
+        EffectKey textureKey = GrGLProgramEffects::GenTextureKey(drawEffect, caps);
+        EffectKey transformKey = GrGLProgramEffects::GenTransformKey(drawEffect);
+        EffectKey attribKey = GrGLProgramEffects::GenAttribKey(drawEffect);
+        static const uint32_t kMetaKeyInvalidMask = ~((uint32_t) SK_MaxU16);
+        if ((textureKey | transformKey | attribKey | fEffectClassID) & kMetaKeyInvalidMask) {
+            return false;
+        }
+
+        // effectKey must be first because it is what will be returned by
+        // GrGLProgramDesc::EffectKeyProvider and passed to the GrGLEffect as its key. 
         b->add32(effectKey);
+        b->add32(textureKey << 16 | transformKey);
+        b->add32(fEffectClassID << 16 | attribKey);
+        return true;
     }
 
     /** Returns a new instance of the appropriate *GL* implementation class
         for the given GrEffect; caller is responsible for deleting
         the object. */
     virtual GrGLEffect* createGLInstance(const GrDrawEffect& drawEffect) const SK_OVERRIDE {
         return SkNEW_ARGS(GLEffect, (*this, drawEffect));
     }
 
-    /** This class is a singleton. This function returns the single instance. */
+    /** This class is a singleton. This function returns the single instance.
+     */
     static const GrBackendEffectFactory& getInstance() {
         static SkAlignedSTStorage<1, GrTBackendEffectFactory> gInstanceMem;
         static const GrTBackendEffectFactory* gInstance;
         if (!gInstance) {
             gInstance = SkNEW_PLACEMENT(gInstanceMem.get(),
                                         GrTBackendEffectFactory);
         }
         return *gInstance;
     }
 
 protected:
-    GrTBackendEffectFactory() {}
+    GrTBackendEffectFactory() {
+        fEffectClassID = GenID();
+    }
 };
 
 #endif