Revert "Revert "Fix lifecycle issue in CommonPool""

This reverts commit 162305aaceca5f6cbaa03db1aa124f67e313612e.

Adjusted tests to ensure they pass on cf_x86

Bug: 129250875
Test: this on cf_x86 & blueline

Change-Id: Ic3245ec8db784ae356b7fa66dda9a2fc91c622ea
diff --git a/libs/hwui/thread/CommonPool.cpp b/libs/hwui/thread/CommonPool.cpp
index 7f94a15..d011bdf 100644
--- a/libs/hwui/thread/CommonPool.cpp
+++ b/libs/hwui/thread/CommonPool.cpp
@@ -49,9 +49,13 @@
     }
 }
 
-void CommonPool::post(Task&& task) {
+CommonPool& CommonPool::instance() {
     static CommonPool pool;
-    pool.enqueue(std::move(task));
+    return pool;
+}
+
+void CommonPool::post(Task&& task) {
+    instance().enqueue(std::move(task));
 }
 
 void CommonPool::enqueue(Task&& task) {
@@ -86,5 +90,18 @@
     }
 }
 
+void CommonPool::waitForIdle() {
+    instance().doWaitForIdle();
+}
+
+void CommonPool::doWaitForIdle() {
+    std::unique_lock lock(mLock);
+    while (mWaitingThreads != THREAD_COUNT) {
+        lock.unlock();
+        usleep(100);
+        lock.lock();
+    }
+}
+
 }  // namespace uirenderer
 }  // namespace android
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