real fix for textblob use after gpu free

gm/textblobuseaftergpufree.cpp

+/*
+ * Copyright 2015 Google Inc.
+ *
+ * Use of this source code is governed by a BD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#include "gm.h"
+
+#if SK_SUPPORT_GPU
+
+#include "SkCanvas.h"
+#include "SkSurface.h"
+#include "SkTextBlob.h"
+
+// This tests that we correctly regenerate textblobs after freeing all gpu resources crbug/491350
+namespace skiagm {
+class TextBlobUseAfterGpuFree : public GM {
+public:
+    TextBlobUseAfterGpuFree() { }
+
+protected:
+    SkString onShortName() override {
+        return SkString("textblobuseaftergpufree");
+    }
+
+    SkISize onISize() override {
+        return SkISize::Make(kWidth, kHeight);
+    }
+
+    void onDraw(SkCanvas* canvas) override {
+        // This GM exists to test a specific feature of the GPU backend.
+        if (NULL == canvas->getGrContext()) {
+            this->drawGpuOnlyMessage(canvas);
+            return;
+        }
+
+        const char text[] = "Hamburgefons";
+
+        SkPaint paint;
+        sk_tool_utils::set_portable_typeface(&paint);
+        paint.setTextSize(20);
+
+        SkTextBlobBuilder builder;
+
+        sk_tool_utils::add_to_text_blob(&builder, text, paint, 10, 10);
+
+        SkAutoTUnref<const SkTextBlob> blob(builder.build());
+
+        // draw textblob
+        SkRect rect = SkRect::MakeLTRB(0.f, 0.f, SkIntToScalar(kWidth), kHeight / 2.f);
+        SkPaint rectPaint;
+        rectPaint.setColor(0xffffffff);
+        canvas->drawRect(rect, rectPaint);
+        canvas->drawTextBlob(blob.get(), 10, 50, paint);
+
+        // This text should look fine
+        canvas->getGrContext()->freeGpuResources();
+        canvas->drawTextBlob(blob.get(), 10, 150, paint);
+    }
+
+private:
+    static const int kWidth = 200;
+    static const int kHeight = 200;
+
+    typedef GM INHERITED;
+};
+
+//////////////////////////////////////////////////////////////////////////////
+
+DEF_GM( return SkNEW(TextBlobUseAfterGpuFree); )
+}
+#endif