Force instantiation in GaussianBlur to hopefully prevent (and diagnose) Chrome crash

BUG=687174

Change-Id: Ieb9930feca9abad9220a1a099e7dd247e6eff70e
Reviewed-on: https://skia-review.googlesource.com/7920
Reviewed-by: Brian Salomon <bsalomon@google.com>
Commit-Queue: Robert Phillips <robertphillips@google.com>

src/core/SkGpuBlurUtils.cpp

@@ -194,6 +194,17 @@ sk_sp<GrRenderTargetContext> GaussianBlur(GrContext* context,
                                           float sigmaY,
                                           SkBackingFit fit) {
     SkASSERT(context);
+
+    {
+        // Chrome is crashing with proxies when they need to be instantiated.
+        // Force an instantiation here (where, in olden days, we used to require a GrTexture)
+        // to see if the input is already un-instantiable.
+        GrTexture* temp = srcProxy->instantiate(context->textureProvider());
+        if (!temp) {
+            return nullptr;
+        }
+    }
+
     SkIRect clearRect;
     int scaleFactorX, radiusX;
     int scaleFactorY, radiusY;