Add a deferred copy surface (take 2)

This CL forces all GrSurface copies to go through a GrSurfaceContext (rather than GrContext).

There is a bit of goofiness going on here until read/writePixels is also consolidated in GrSurfaceContext and a proxy-backed SkImage/SkSurface is added.

This is a reland of https://skia-review.googlesource.com/c/5773/ (Add a deferred copy surface)

Change-Id: Ide560f569aede5e622420dc2f30eef76357d69f4
Reviewed-on: https://skia-review.googlesource.com/5939
Reviewed-by: Brian Osman <brianosman@google.com>
Reviewed-by: Brian Salomon <bsalomon@google.com>
Commit-Queue: Robert Phillips <robertphillips@google.com>
diff --git a/src/gpu/GrContext.cpp b/src/gpu/GrContext.cpp
index ff5b026..2e66c0c 100644
--- a/src/gpu/GrContext.cpp
+++ b/src/gpu/GrContext.cpp
@@ -541,43 +541,6 @@
     fDrawingManager->prepareSurfaceForExternalIO(surface);
 }
 
-bool GrContext::copySurface(GrSurface* dst, GrSurface* src, const SkIRect& srcRect,
-                            const SkIPoint& dstPoint) {
-    ASSERT_SINGLE_OWNER
-    RETURN_FALSE_IF_ABANDONED
-    GR_AUDIT_TRAIL_AUTO_FRAME(&fAuditTrail, "GrContext::copySurface");
-
-    if (!src || !dst) {
-        return false;
-    }
-    ASSERT_OWNED_RESOURCE(src);
-    ASSERT_OWNED_RESOURCE(dst);
-
-    // We don't allow conversion between integer configs and float/fixed configs.
-    if (GrPixelConfigIsSint(dst->config()) != GrPixelConfigIsSint(src->config())) {
-        return false;
-    }
-
-#ifndef ENABLE_MDB
-    // We can't yet fully defer copies to textures, so GrTextureContext::copySurface will
-    // execute the copy immediately. Ensure the data is ready.
-    src->flushWrites();
-#endif
-
-    sk_sp<GrSurfaceContext> surfaceContext(
-        this->contextPriv().makeWrappedSurfaceContext(sk_ref_sp(dst)));
-
-    if (!surfaceContext) {
-        return false;
-    }
-
-    if (!surfaceContext->copySurface(src, srcRect, dstPoint)) {
-        return false;
-    }
-
-    return true;
-}
-
 void GrContext::flushSurfaceWrites(GrSurface* surface) {
     ASSERT_SINGLE_OWNER
     RETURN_IF_ABANDONED
@@ -639,8 +602,36 @@
     }
 }
 
+sk_sp<GrSurfaceContext> GrContextPriv::makeDeferredSurfaceContext(const GrSurfaceDesc& dstDesc,
+                                                                  SkBudgeted isDstBudgeted) {
+
+    sk_sp<GrSurfaceProxy> proxy = GrSurfaceProxy::MakeDeferred(*fContext->caps(), dstDesc,
+                                                               SkBackingFit::kExact, isDstBudgeted);
+
+    if (proxy->asRenderTargetProxy()) {
+        return this->drawingManager()->makeRenderTargetContext(std::move(proxy), nullptr, nullptr);
+    } else {
+        SkASSERT(proxy->asTextureProxy());
+        return this->drawingManager()->makeTextureContext(std::move(proxy));
+    }
+
+    return nullptr;
+}
+
+sk_sp<GrSurfaceContext> GrContextPriv::makeTestSurfaceContext(sk_sp<GrSurfaceProxy> proxy) {
+
+    if (proxy->asRenderTargetProxy()) {
+        return this->drawingManager()->makeRenderTargetContext(std::move(proxy), nullptr, nullptr);
+    } else {
+        SkASSERT(proxy->asTextureProxy());
+        return this->drawingManager()->makeTextureContext(std::move(proxy));
+    }
+
+    return nullptr;
+}
+
 sk_sp<GrRenderTargetContext> GrContextPriv::makeBackendTextureRenderTargetContext(
-                                                                   const GrBackendTextureDesc& desc, 
+                                                                   const GrBackendTextureDesc& desc,
                                                                    sk_sp<SkColorSpace> colorSpace,
                                                                    const SkSurfaceProps* props,
                                                                    GrWrapOwnership ownership) {