Refactor legacy FrameBuffer to use EncodedImageBuffer::Realloc

Preparation for deleting VCMEncodedFrame::VerifyAndAllocate and
EncodedImage::Allocate.

Bug: webrtc:9378
Change-Id: If7c16061962bbd58c3e7d5720189854e00a3d7bf
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/154570
Reviewed-by: Philip Eliasson <philipel@webrtc.org>
Commit-Queue: Niels Moller <nisse@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#29339}
diff --git a/modules/video_coding/frame_buffer.cc b/modules/video_coding/frame_buffer.cc
index c49cde6..755acb2 100644
--- a/modules/video_coding/frame_buffer.cc
+++ b/modules/video_coding/frame_buffer.cc
@@ -101,7 +101,7 @@
   uint32_t requiredSizeBytes =
       size() + packet.sizeBytes +
       (packet.insertStartCode ? kH264StartCodeLengthBytes : 0);
-  if (requiredSizeBytes >= capacity()) {
+  if (requiredSizeBytes > capacity()) {
     const uint8_t* prevBuffer = data();
     const uint32_t increments =
         requiredSizeBytes / kBufferIncStepSizeBytes +
@@ -112,7 +112,15 @@
                            "big.";
       return kSizeError;
     }
-    VerifyAndAllocate(newSize);
+    if (data() == nullptr) {
+      encoded_image_buffer_ = EncodedImageBuffer::Create(newSize);
+      SetEncodedData(encoded_image_buffer_);
+      set_size(0);
+    } else {
+      RTC_CHECK(encoded_image_buffer_ != nullptr);
+      RTC_DCHECK_EQ(encoded_image_buffer_->data(), data());
+      encoded_image_buffer_->Realloc(newSize);
+    }
     _sessionInfo.UpdateDataPointers(prevBuffer, data());
   }