[ Profiler ] Fix CPU sample streaming sending only a single sample block instead of a chain of blocks

A pointer to a single SampleBlockBuffer was being passed in while
building a profile instead of a reference to SampleBlockListProcessor.
This also could lead to a segfault if there were no blocks to process.

TEST=CQ + manual testing in Flutter engine

Change-Id: I1e2903cf718da7b32747553c2ed1efcb78b62c86
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/214441
Commit-Queue: Ben Konyi <bkonyi@google.com>
Reviewed-by: Siva Annamalai <asiva@google.com>

https://dart.googlesource.com/sdk/+/7786183e144df65b5411163caf8abe8b7e93df62
diff --git a/commits.json b/commits.json
index b227e31..c08f4bf 100644
--- a/commits.json
+++ b/commits.json
@@ -1,5 +1,5 @@
 {
   "external/github.com/flutter/engine":"5f7d0053f98dd5284f69514504e8b0f318ac9f13",
   "external/github.com/flutter/flutter":"69ae50310b07f8ef80fd1f14af8209adb2b83f03",
-  "sdk":"70533ae7fa89c28dffe6ae1e693c124278ff6a34"
+  "sdk":"7786183e144df65b5411163caf8abe8b7e93df62"
 }
\ No newline at end of file