Introduced the render sample queue for the aec and aecm.

BUG=webrtc:5099

Review URL: https://codereview.webrtc.org/1410833002

Cr-Commit-Position: refs/heads/master@{#10662}

webrtc/modules/audio_processing/processing_component.h

@@ -17,6 +17,22 @@
 
 namespace webrtc {
 
+// Functor to use when supplying a verifier function for the queue item
+// verifcation.
+template <typename T>
+class RenderQueueItemVerifier {
+ public:
+  explicit RenderQueueItemVerifier(size_t minimum_capacity)
+      : minimum_capacity_(minimum_capacity) {}
+
+  bool operator()(const std::vector<T>& v) const {
+    return v.capacity() >= minimum_capacity_;
+  }
+
+ private:
+  size_t minimum_capacity_;
+};
+
 class ProcessingComponent {
  public:
   ProcessingComponent();