Enable blend optimizations with instanced draws

src/gpu/GrDrawingManager.cpp

Index: src/gpu/GrDrawingManager.cpp
diff --git a/src/gpu/GrDrawingManager.cpp b/src/gpu/GrDrawingManager.cpp
index 458bd20571fafc332fff5cb2bd66accd1bde31f9..75ee0db7c8979a41bc24c3af2d9ef1efa17be952 100644
--- a/src/gpu/GrDrawingManager.cpp
+++ b/src/gpu/GrDrawingManager.cpp
@@ -13,9 +13,13 @@
 #include "GrSoftwarePathRenderer.h"
 #include "SkTTopoSort.h"
 
+#include "instanced/InstancedRendering.h"
+
 #include "text/GrAtlasTextContext.h"
 #include "text/GrStencilAndCoverTextContext.h"
 
+using gr_instanced::InstancedRendering;
+
 void GrDrawingManager::cleanup() {
     for (int i = 0; i < fDrawTargets.count(); ++i) {
         fDrawTargets[i]->makeClosed();  // no drawTarget should receive a new command after this
@@ -40,6 +44,11 @@ GrDrawingManager::~GrDrawingManager() {
 
 void GrDrawingManager::abandon() {
     fAbandoned = true;
+    for (int i = 0; i < fDrawTargets.count(); ++i) {
+        if (InstancedRendering* ir = fDrawTargets[i]->instancedRendering()) {
+            ir->resetGpuResources(InstancedRendering::ResetType::kAbandon);
+        }
+    }
     this->cleanup();
 }
 
@@ -48,6 +57,11 @@ void GrDrawingManager::freeGpuResources() {
     delete fPathRendererChain;
     fPathRendererChain = nullptr;
     SkSafeSetNull(fSoftwarePathRenderer);
+    for (int i = 0; i < fDrawTargets.count(); ++i) {
+        if (InstancedRendering* ir = fDrawTargets[i]->instancedRendering()) {
+            ir->resetGpuResources(InstancedRendering::ResetType::kDestroy);
+        }
+    }
 }
 
 void GrDrawingManager::reset() {