Dependencies are now added between the drawTargets in GrPipeline

src/gpu/GrDrawTarget.cpp

Index: src/gpu/GrDrawTarget.cpp
diff --git a/src/gpu/GrDrawTarget.cpp b/src/gpu/GrDrawTarget.cpp
index 5a3feccc1753e44f8c57cfd0d45602dd0ef76c4d..7b1464ca7fb94d3151d785dc1c57d03e4eafd68a 100644
--- a/src/gpu/GrDrawTarget.cpp
+++ b/src/gpu/GrDrawTarget.cpp
@@ -32,7 +32,7 @@
 
 ////////////////////////////////////////////////////////////////////////////////
 
-GrDrawTarget::GrDrawTarget(GrGpu* gpu, GrResourceProvider* resourceProvider,
+GrDrawTarget::GrDrawTarget(GrRenderTarget* rt, GrGpu* gpu, GrResourceProvider* resourceProvider,
                            const Options& options)
     : fGpu(SkRef(gpu))
     , fResourceProvider(resourceProvider)
@@ -40,7 +40,8 @@ GrDrawTarget::GrDrawTarget(GrGpu* gpu, GrResourceProvider* resourceProvider,
     , fFlushing(false)
     , fFirstUnpreparedBatch(0)
     , fFlags(0)
-    , fOptions(options) {
+    , fOptions(options)
+    , fRenderTarget(rt) {
     // TODO: Stop extracting the context (currently needed by GrClipMaskManager)
     fContext = fGpu->getContext();
     fClipMaskManager.reset(new GrClipMaskManager(this));
@@ -52,6 +53,10 @@ GrDrawTarget::GrDrawTarget(GrGpu* gpu, GrResourceProvider* resourceProvider,
 }
 
 GrDrawTarget::~GrDrawTarget() {
+    if (fRenderTarget && this == fRenderTarget->getLastDrawTarget()) {
+        fRenderTarget->setLastDrawTarget(nullptr);
+    }
+
     fGpu->unref();
 }
 
@@ -184,7 +189,7 @@ void GrDrawTarget::flush() {
     // drawTargets will be created to replace them if the SkGpuDevice(s) write to them again.
     this->makeClosed();
 
-    // Loop over all batches and generate geometry
+    // Loop over the batches that haven't yet generated their geometry
     for (; fFirstUnpreparedBatch < fBatches.count(); ++fFirstUnpreparedBatch) {
         fBatches[fFirstUnpreparedBatch]->prepare(&fFlushState);
     }
@@ -227,6 +232,11 @@ void GrDrawTarget::drawBatch(const GrPipelineBuilder& pipelineBuilder, GrDrawBat
         return;
     }
 
+#ifdef ENABLE_MDB
+    SkASSERT(fRenderTarget);
+    batch->pipeline()->addDependenciesTo(fRenderTarget);
+#endif
+
     this->recordBatch(batch);
 }
 
@@ -455,6 +465,10 @@ void GrDrawTarget::copySurface(GrSurface* dst,
                                const SkIPoint& dstPoint) {
     GrBatch* batch = GrCopySurfaceBatch::Create(dst, src, srcRect, dstPoint);
     if (batch) {
+#ifdef ENABLE_MDB
+        this->addDependency(src);
+#endif
+
         this->recordBatch(batch);
         batch->unref();
     }