media: Use base::flat_map<>::contains()

Use `base::flat_map<>::contains()` instead of `find()` and `count()` for
the better code readability:
* It is less readable and could easily lead another bugs if we mix up
  using `find()`, `count()` and `end()` methods of STL map or chromium
  flat_map.
* Replaced with `contains()` method for `base::flat_map<>`
  (chromium/src/base/containers/flat_map.h) only since C++20 is not
  supported yet for Chromium (go/cpp-chrome).
* Target path: /src/media
* Exception: Did not replace them if the iterator returned by `find
  ()` method is used in the code.

```
autoninja -C out/Default media_unittests
out/Default/media_unittests
```

Bug: 1332591
Change-Id: Idf5374daf26c777672a6c4a672e5b51e5155ed79
Test: All tests passed on an instance of Linux cloudtop
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3696614
Reviewed-by: Xiaohan Wang <xhwang@chromium.org>
Reviewed-by: Daniel Cheng <dcheng@chromium.org>
Commit-Queue: Sangbaek Park <sangbaekpark@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1014130}

media/audio/audio_output_dispatcher_impl.cc

@@ -75,8 +75,7 @@ bool AudioOutputDispatcherImpl::StartStream(
     AudioOutputStream::AudioSourceCallback* callback,
     AudioOutputProxy* stream_proxy) {
   DCHECK(audio_manager()->GetTaskRunner()->BelongsToCurrentThread());
-  DCHECK(proxy_to_physical_map_.find(stream_proxy) ==
-         proxy_to_physical_map_.end());
+  DCHECK(!proxy_to_physical_map_.contains(stream_proxy));
 
   if (idle_streams_.empty() && !CreateAndOpenStream())
     return false;

media/base/android/android_cdm_factory.cc

@@ -99,7 +99,7 @@ void AndroidCdmFactory::OnCdmCreated(
     const std::string& error_message) {
   DVLOG(1) << __func__ << ": creation_id = " << creation_id;
 
-  DCHECK(pending_creations_.count(creation_id));
+  DCHECK(pending_creations_.contains(creation_id));
   CdmCreatedCB cdm_created_cb =
       std::move(pending_creations_[creation_id].second);
   pending_creations_.erase(creation_id);

media/base/mime_util_internal.cc

@@ -424,8 +424,7 @@ void MimeUtil::AddContainerWithCodecs(const std::string& mime_type,
 }
 
 bool MimeUtil::IsSupportedMediaMimeType(const std::string& mime_type) const {
-  return media_format_map_.find(base::ToLowerASCII(mime_type)) !=
-         media_format_map_.end();
+  return media_format_map_.contains(base::ToLowerASCII(mime_type));
 }
 
 void MimeUtil::SplitCodecs(const std::string& codecs,

media/fuchsia/cdm/fuchsia_cdm.cc

@@ -407,7 +407,7 @@ void FuchsiaCdm::OnCreateSession(std::unique_ptr<CdmSession> session,
   }
 
   session->set_session_id(session_id);
-  DCHECK(session_map_.find(session_id) == session_map_.end())
+  DCHECK(!session_map_.contains(session_id))
       << "Duplicated session id " << session_id;
   session_map_[session_id] = std::move(session);
 }
@@ -467,7 +467,7 @@ void FuchsiaCdm::OnSessionLoaded(std::unique_ptr<CdmSession> session,
   }
 
   std::string session_id = session->session_id();
-  DCHECK(session_map_.find(session_id) == session_map_.end())
+  DCHECK(!session_map_.contains(session_id))
       << "Duplicated session id " << session_id;
 
   session_map_.emplace(session_id, std::move(session));

media/fuchsia/common/stream_processor_helper.cc

@@ -104,7 +104,7 @@ void StreamProcessorHelper::Process(IoPacket input) {
                                         fidl::Clone(input.format()));
   }
 
-  DCHECK(input_packets_.find(input.buffer_index()) == input_packets_.end());
+  DCHECK(!input_packets_.contains(input.buffer_index()));
   input_packets_.insert_or_assign(input.buffer_index(), std::move(input));
   processor_->QueueInputPacket(std::move(packet));
 }

media/gpu/mac/vt_video_decode_accelerator_mac.cc

@@ -1086,8 +1086,8 @@ void VTVideoDecodeAccelerator::DecodeTaskH264(
           }
 
           // Record the configuration.
-          DCHECK(seen_pps_.count(slice_hdr.pic_parameter_set_id));
-          DCHECK(seen_sps_.count(pps->seq_parameter_set_id));
+          DCHECK(seen_pps_.contains(slice_hdr.pic_parameter_set_id));
+          DCHECK(seen_sps_.contains(pps->seq_parameter_set_id));
           active_sps_ = seen_sps_[pps->seq_parameter_set_id];
           // Note: SPS extension lookup may create an empty entry.
           active_spsext_ = seen_spsext_[pps->seq_parameter_set_id];
@@ -1481,9 +1481,9 @@ void VTVideoDecodeAccelerator::DecodeTaskHEVC(
         }
 
         // Record the configuration.
-        DCHECK(seen_pps_.count(curr_slice_hdr->slice_pic_parameter_set_id));
-        DCHECK(seen_sps_.count(pps->pps_seq_parameter_set_id));
-        DCHECK(seen_vps_.count(sps->sps_video_parameter_set_id));
+        DCHECK(seen_pps_.contains(curr_slice_hdr->slice_pic_parameter_set_id));
+        DCHECK(seen_sps_.contains(pps->pps_seq_parameter_set_id));
+        DCHECK(seen_vps_.contains(sps->sps_video_parameter_set_id));
         active_vps_ = seen_vps_[sps->sps_video_parameter_set_id];
         active_sps_ = seen_sps_[pps->pps_seq_parameter_set_id];
         active_pps_ = seen_pps_[curr_slice_hdr->slice_pic_parameter_set_id];
@@ -1696,7 +1696,7 @@ void VTVideoDecodeAccelerator::DecodeDone(Frame* frame) {
 
   // pending_frames_.erase() will delete |frame|.
   int32_t bitstream_id = frame->bitstream_id;
-  DCHECK_EQ(1u, pending_frames_.count(bitstream_id));
+  DCHECK(pending_frames_.contains(bitstream_id));
 
   if (state_ == STATE_ERROR || state_ == STATE_DESTROYING) {
     // Destroy() handles NotifyEndOfBitstreamBuffer().
@@ -1809,7 +1809,7 @@ void VTVideoDecodeAccelerator::AssignPictureBuffers(
 
   for (const PictureBuffer& picture : pictures) {
     DVLOG(3) << "AssignPictureBuffer(" << picture.id() << ")";
-    DCHECK(!picture_info_map_.count(picture.id()));
+    DCHECK(!picture_info_map_.contains(picture.id()));
     assigned_picture_ids_.insert(picture.id());
     available_picture_ids_.push_back(picture.id());
     if (picture.client_texture_ids().empty() &&

media/learning/impl/random_tree_trainer.cc

@@ -78,7 +78,7 @@ struct InteriorNode : public Model {
 
   // Add |child| has the node for feature value |v|.
   void AddChild(FeatureValue v, std::unique_ptr<Model> child) {
-    DCHECK_EQ(children_.count(v), 0u);
+    DCHECK(!children_.contains(v));
     children_.emplace(v, std::move(child));
   }
 

media/renderers/win/media_foundation_texture_pool.cc

@@ -122,8 +122,9 @@ ComPtr<ID3D11Texture2D> MediaFoundationTexturePool::AcquireTexture(
 
 void MediaFoundationTexturePool::ReleaseTexture(
     const base::UnguessableToken& texture_token) {
-  if (texture_pool_.count(texture_token) > 0) {
-    texture_pool_.at(texture_token).texture_in_use_ = false;
+  auto it = texture_pool_.find(texture_token);
+  if (it != texture_pool_.end()) {
+    it->second.texture_in_use_ = false;
   }
 }