Add debugging helper to GrDrawTarget

This CL relies on https://codereview.chromium.org/1414773002/ (Add the machinery to GrDrawTarget to enable topological sorting)

BUG=skia:4094

Review URL: https://codereview.chromium.org/1416753002

src/gpu/GrContext.cpp

@@ -100,6 +100,7 @@ void GrDrawingManager::flush() {
     SkASSERT(result);
 
     for (int i = 0; i < fDrawTargets.count(); ++i) {
+        //SkDEBUGCODE(fDrawTargets[i]->dump();)
         fDrawTargets[i]->flush();
     }
 

src/gpu/GrDrawTarget.cpp

@@ -42,6 +42,11 @@ GrDrawTarget::GrDrawTarget(GrGpu* gpu, GrResourceProvider* resourceProvider)
     // TODO: Stop extracting the context (currently needed by GrClipMaskManager)
     fContext = fGpu->getContext();
     fClipMaskManager.reset(new GrClipMaskManager(this));
+
+#ifdef SK_DEBUG
+    static int debugID = 0;
+    fDebugID = debugID++;
+#endif
 }
 
 GrDrawTarget::~GrDrawTarget() {
@@ -79,6 +84,29 @@ void GrDrawTarget::addDependency(GrSurface* dependedOn) {
     }
 }
 
+#ifdef SK_DEBUG
+void GrDrawTarget::dump() const {
+    SkDebugf("--------------------------------------------------------------\n");
+    SkDebugf("node: %d\n");
+    SkDebugf("relies On (%d): ", fDependencies.count());
+    for (int i = 0; i < fDependencies.count(); ++i) {
+        SkDebugf("%d, ", fDependencies[i]->fDebugID);
+    }
+    SkDebugf("\n");
+    SkDebugf("batches (%d):\n", fBatches.count());
+    for (int i = 0; i < fBatches.count(); ++i) {
+#if 0
+        SkDebugf("*******************************\n");
+#endif
+        SkDebugf("%d: %s\n", i, fBatches[i]->name());
+#if 0
+        SkString str = fBatches[i]->dumpInfo();
+        SkDebugf("%s\n", str.c_str());
+#endif
+    }
+}
+#endif
+
 bool GrDrawTarget::setupDstReadIfNecessary(const GrPipelineBuilder& pipelineBuilder,
                                            const GrProcOptInfo& colorPOI,
                                            const GrProcOptInfo& coveragePOI,

src/gpu/GrDrawTarget.h

@@ -70,6 +70,11 @@ public:
         return fDependencies.find(dependedOn) >= 0;
     }
 
+    /*
+     * Dump out the drawTarget dependency DAG
+     */
+    SkDEBUGCODE(void dump() const;)
+
     /**
      * Empties the draw buffer of any queued up draws.
      */
@@ -304,6 +309,7 @@ private:
     bool                                        fFlushing;
     int                                         fFirstUnpreparedBatch;
 
+    SkDEBUGCODE(int                             fDebugID;)
     uint32_t                                    fFlags;
 
     // 'this' drawTarget relies on the output of the drawTargets in 'fDependencies'