Stop flattening GrCoordTransforms in parent GrFragmentProcessors.

include/gpu/GrFragmentProcessor.h

Index: include/gpu/GrFragmentProcessor.h
diff --git a/include/gpu/GrFragmentProcessor.h b/include/gpu/GrFragmentProcessor.h
index 6864702b600fb443bb3cacd1922424b295ce00c1..270ee16515a61508e5bcb464099c70651335ea7e 100644
--- a/include/gpu/GrFragmentProcessor.h
+++ b/include/gpu/GrFragmentProcessor.h
@@ -14,6 +14,7 @@ class GrCoordTransform;
 class GrGLSLCaps;
 class GrGLSLFragmentProcessor;
 class GrInvariantOutput;
+class GrPipeline;
 class GrProcessorKeyBuilder;
 
 /** Provides custom fragment shader code. Fragment processors receive an input color (vec4f) and
@@ -68,8 +69,7 @@ public:
         , fUsesDistanceVectorField(false)
         , fUsesLocalCoords(false)
         , fNumTexturesExclChildren(0)
-        , fNumBuffersExclChildren(0)
-        , fNumTransformsExclChildren(0) {}
+        , fNumBuffersExclChildren(0) {}
 
     ~GrFragmentProcessor() override;
 
@@ -86,9 +86,7 @@ public:
 
     int numBuffersExclChildren() const { return fNumBuffersExclChildren; }
 
-    int numTransformsExclChildren() const { return fNumTransformsExclChildren; }
-
-    int numTransforms() const { return fCoordTransforms.count(); }
+    int numCoordTransforms() const { return fCoordTransforms.count(); }
 
     /** Returns the coordinate transformation at index. index must be valid according to
         numTransforms(). */
@@ -135,6 +133,40 @@ public:
         this->onComputeInvariantOutput(inout);
     }
 
+    /**
+     * Pre-order traversal of a FP hierarchy, or of the forest of FPs in a GrPipeline. In the latter
+     * case the tree rooted at each FP in the GrPipeline is visited successively.
+     * */
+    class Iter : public SkNoncopyable {
+    public:
+        explicit Iter(const GrFragmentProcessor* fp) { fFPStack.push_back(fp); }
+        explicit Iter(const GrPipeline& pipeline);
+        const GrFragmentProcessor* next();
+
+    private:
+        SkSTArray<4, const GrFragmentProcessor*, true> fFPStack;
+    };
+
+    /**
+     * Iterates over all the GrCoordTransforms in a GrPipeline's GrFragmentProcessors. FPs are
+     * visited in the same order as Iter and each of an FP's coord transforms are visited linearly.
+     */
+    class CoordTransformIter : public SkNoncopyable {
+    public:
+        explicit CoordTransformIter(const GrPipeline& pipeline)
+                : fCurrFP(nullptr)
+                , fCTIdx(0)
+                , fFPIter(pipeline) {
+            fCurrFP = fFPIter.next();
+        }
+        const GrCoordTransform* next();
+
+    private:
+        const GrFragmentProcessor*  fCurrFP;
+        int                         fCTIdx;
+        GrFragmentProcessor::Iter   fFPIter;
+    };
+
 protected:
     void addTextureAccess(const GrTextureAccess* textureAccess) override;
     void addBufferAccess(const GrBufferAccess*) override;
@@ -206,15 +238,18 @@ private:
 
     bool                                       fUsesLocalCoords;
 
+    SkSTArray<4, const GrCoordTransform*, true> fCoordTransforms;
+
     /**
-     * fCoordTransforms stores the transforms of this proc, followed by all the transforms of this
-     * proc's children. In other words, each proc stores all the transforms of its subtree as if
+     * A processor stores the texture accesses of this proc, followed by all the accesses of this
+     * proc's children. In other words, each proc stores all the accesses of its subtree as if
      * they were collected using preorder traversal.
      *
      * Example:
      * Suppose we have frag proc A, who has two children B and D. B has a child C, and D has
-     * two children E and F. Suppose procs A, B, C, D, E, F have 1, 2, 1, 1, 3, 2 transforms
-     * respectively. The following shows what the fCoordTransforms array of each proc would contain:
+     * two children E and F. Suppose procs A, B, C, D, E, F have 1, 2, 1, 1, 3, 2 accesses
+     * respectively. The following shows what the array of each proc's texture accesses would
+     * contain:
      *
      *                                   (A)
      *                        [a1,b1,b2,c1,d1,e1,e2,e3,f1,f2]
@@ -227,12 +262,10 @@ private:
      *                      (C)          (E)          (F)
      *                     [c1]      [e1,e2,e3]      [f1,f2]
      *
-     * The same goes for fTextureAccesses with textures.
+     * The same goes for buffer accesses.
      */
-    SkSTArray<4, const GrCoordTransform*, true> fCoordTransforms;
     int                                         fNumTexturesExclChildren;
     int                                         fNumBuffersExclChildren;
-    int                                         fNumTransformsExclChildren;
 
     /**
      * This is not SkSTArray<1, sk_sp<GrFragmentProcessor>> because this class holds strong