Revert "Revert "Add ExternalTexture class into RenderEngine inte..."

Revert submission 14199598-revert-14086921-renderengine-external-tex-QJNBWQMQEU

Reason for revert: Prepare for relanding
Reverted Changes:
I01e65a7f4:Revert "Update WaylandRenderSurface to accomodate ...
I7d58118c1:Revert "Update Readback VTS to align with RenderEn...
I1501890f4:Revert "Add ExternalTexture class into RenderEngin...

Added the following fixes:
1. CachedSet renders to intermediate texture variable rather than
mTexture directly, since mTexture is not guaranteed to be nonnull.
2. Add null check when setting new buffer in BLAST.

Bug: 185524947
Bug: 180767535
Test: builds, boots
Test: librenderengine_test
Change-Id: I52ea82e24336b496d996bbe3e445db0affe1abb8
diff --git a/services/surfaceflinger/ClientCache.cpp b/services/surfaceflinger/ClientCache.cpp
index 44b33ef..f310738 100644
--- a/services/surfaceflinger/ClientCache.cpp
+++ b/services/surfaceflinger/ClientCache.cpp
@@ -102,7 +102,12 @@
         return false;
     }
 
-    processBuffers[id].buffer = buffer;
+    LOG_ALWAYS_FATAL_IF(mRenderEngine == nullptr,
+                        "Attempted to build the ClientCache before a RenderEngine instance was "
+                        "ready!");
+    processBuffers[id].buffer = std::make_shared<
+            renderengine::ExternalTexture>(buffer, *mRenderEngine,
+                                           renderengine::ExternalTexture::Usage::READABLE);
     return true;
 }
 
@@ -132,7 +137,7 @@
     }
 }
 
-sp<GraphicBuffer> ClientCache::get(const client_cache_t& cacheId) {
+std::shared_ptr<renderengine::ExternalTexture> ClientCache::get(const client_cache_t& cacheId) {
     std::lock_guard lock(mMutex);
 
     ClientCacheBuffer* buf = nullptr;
@@ -213,8 +218,8 @@
         auto &buffers = i.second.second;
         for (auto& [id, clientCacheBuffer] : buffers) {
             StringAppendF(&result, "\t ID: %d, Width/Height: %d,%d\n", (int)id,
-                          (int)clientCacheBuffer.buffer->getWidth(),
-                          (int)clientCacheBuffer.buffer->getHeight());
+                          (int)clientCacheBuffer.buffer->getBuffer()->getWidth(),
+                          (int)clientCacheBuffer.buffer->getBuffer()->getHeight());
         }
     }
 }