Add GrExternalTextureData and SkCrossContextImageData

GrExternalTextureData is an API for exporting the backend-specific
information about a texture in a type-safe way, and without pointing
into the GrTexture. The new detachBackendTexture API lets us release
ownership of a texture to the client.

SkCrossContextImageData is the public API that lets clients upload
textures on one thread/GrContext, then safely transfer ownership to
another thread and GrContext for rendering.

Only GL is implemented/supported right now. Vulkan support requires
that we add thread-safe memory pools, or otherwise transfer the
actual memory block containing the texture to the new context.

Re-land of https://skia-review.googlesource.com/c/8529/

BUG=skia:

Change-Id: I48ebd57d1ea0cfd3a1db10c475f2903afb821966
Reviewed-on: https://skia-review.googlesource.com/8960
Reviewed-by: Brian Salomon <bsalomon@google.com>
Commit-Queue: Brian Osman <brianosman@google.com>

1 files changed, 11 insertions, 0 deletions

diff --git a/src/gpu/GrGpuResource.cpp b/src/gpu/GrGpuResource.cpp
index c3a9556588..dcc4e62282 100644
--- a/src/gpu/GrGpuResource.cpp
+++ b/src/gpu/GrGpuResource.cpp
@@ -43,6 +43,17 @@ void GrGpuResource::registerWithCacheWrapped() {
     get_resource_cache(fGpu)->resourceAccess().insertResource(this);
 }
 
+void GrGpuResource::detachFromCache() {
+    if (this->wasDestroyed()) {
+        return;
+    }
+    if (fUniqueKey.isValid()) {
+        this->removeUniqueKey();
+    }
+    this->removeScratchKey();
+    this->makeUnbudgeted();
+}
+
 GrGpuResource::~GrGpuResource() {
     // The cache should have released or destroyed this resource.
     SkASSERT(this->wasDestroyed());