Add abandoned GPU check to createTextureProxy

I'm guessing the crash is actually on the first 'fGpu' reference in createTextureProxy after the GPU context has been abandoned.

Bug: 712929
Change-Id: Ia6742da7073c2320e592b42fcf2d0e7c04eeefb9
Reviewed-on: https://skia-review.googlesource.com/13966
Reviewed-by: Greg Daniel <egdaniel@google.com>
Commit-Queue: Robert Phillips <robertphillips@google.com>

src/gpu/GrResourceProvider.cpp

@@ -123,6 +123,12 @@ static bool make_info(int w, int h, GrPixelConfig config, SkImageInfo* ii) {
 sk_sp<GrTextureProxy> GrResourceProvider::createTextureProxy(const GrSurfaceDesc& desc,
                                                              SkBudgeted budgeted,
                                                              const GrMipLevel& mipLevel) {
+    ASSERT_SINGLE_OWNER
+
+    if (this->isAbandoned()) {
+        return nullptr;
+    }
+
     if (!mipLevel.fPixels) {
         return nullptr;
     }