Revert "Have a GrBackendFormat be stored on gpu proxies."

This reverts commit 51b1c12bbc2fa3f8d4faa29ad19c6f3cb34837ce.

Reason for revert: reverting till flutter gets to 1.1 to fix build issues.

Original change's description:
> Have a GrBackendFormat be stored on gpu proxies.
>
> Bug: skia:
> Change-Id: Iaf1fb24ab29a61d44e5fa59a5e0867ed02dcda90
> Reviewed-on: https://skia-review.googlesource.com/c/168021
> Reviewed-by: Brian Osman <brianosman@google.com>
> Commit-Queue: Greg Daniel <egdaniel@google.com>

TBR=egdaniel@google.com,bsalomon@google.com,brianosman@google.com

Change-Id: I574fdc084ef5994596c51fb0d60423b5dc01b885
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: chromium:903701 chromium:903756
Reviewed-on: https://skia-review.googlesource.com/c/169835
Commit-Queue: Greg Daniel <egdaniel@google.com>
Reviewed-by: Greg Daniel <egdaniel@google.com>
diff --git a/tests/GrMeshTest.cpp b/tests/GrMeshTest.cpp
index ccb4acd..163dec6 100644
--- a/tests/GrMeshTest.cpp
+++ b/tests/GrMeshTest.cpp
@@ -83,12 +83,9 @@
 DEF_GPUTEST_FOR_RENDERING_CONTEXTS(GrMeshTest, reporter, ctxInfo) {
     GrContext* context = ctxInfo.grContext();
 
-    const GrBackendFormat format =
-            context->contextPriv().caps()->getBackendFormatFromColorType(kRGBA_8888_SkColorType);
-
     sk_sp<GrRenderTargetContext> rtc(context->contextPriv().makeDeferredRenderTargetContext(
-                                                 format, SkBackingFit::kExact, kImageWidth,
-                                                 kImageHeight, kRGBA_8888_GrPixelConfig, nullptr));
+                                                 SkBackingFit::kExact, kImageWidth, kImageHeight,
+                                                 kRGBA_8888_GrPixelConfig, nullptr));
     if (!rtc) {
         ERRORF(reporter, "could not create render target context.");
         return;