Refactor mime type resource counts in AdsPLMO

This a precursor change that tracks mime type counts for all
resource types in frames. This will allow future changes to record
other mime types without adding separate counters to FrameData.

Bug: 951480
Change-Id: I700c8ce9f3065082a621ce8e69027fa8607105e7
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1562291Reviewed-by: Ryan Sturm <ryansturm@chromium.org>
Commit-Queue: John Delaney <johnidel@chromium.org>
Cr-Commit-Position: refs/heads/master@{#649667}

chrome/browser/page_load_metrics/observers/ad_metrics/ads_page_load_metrics_observer.cc

@@ -485,9 +485,12 @@ void AdsPageLoadMetricsObserver::RecordPageResourceTotalHistograms(
   ukm::builders::AdPageLoad builder(source_id);
   builder.SetTotalBytes(aggregate_frame_data_->network_bytes() >> 10)
       .SetAdBytes(aggregate_frame_data_->ad_network_bytes() >> 10)
-      .SetAdJavascriptBytes(
-          aggregate_frame_data_->ad_javascript_network_bytes() >> 10)
-      .SetAdVideoBytes(aggregate_frame_data_->ad_video_network_bytes() >> 10);
+      .SetAdJavascriptBytes(aggregate_frame_data_->GetAdNetworkBytesForMime(
+                                FrameData::ResourceMimeType::kJavascript) >>
+                            10)
+      .SetAdVideoBytes(aggregate_frame_data_->GetAdNetworkBytesForMime(
+                           FrameData::ResourceMimeType::kVideo) >>
+                       10);
   base::TimeTicks current_time = clock_->NowTicks();
   if (!time_commit_.is_null()) {
     int time_since_commit = (current_time - time_commit_).InMicroseconds();

chrome/browser/page_load_metrics/observers/ad_metrics/frame_data.cc

@@ -112,10 +112,7 @@ void FrameData::ProcessResourceLoadInFrame(
       ad_bytes_ += resource->encoded_body_length;
 
     ResourceMimeType mime_type = GetResourceMimeType(resource);
-    if (mime_type == ResourceMimeType::kVideo)
-      ad_video_network_bytes_ += resource->delta_bytes;
-    else if (mime_type == ResourceMimeType::kJavascript)
-      ad_javascript_network_bytes_ += resource->delta_bytes;
+    ad_bytes_by_mime_[static_cast<size_t>(mime_type)] += resource->delta_bytes;
   }
 }
 
@@ -123,11 +120,7 @@ void FrameData::AdjustAdBytes(int64_t unaccounted_ad_bytes,
                               ResourceMimeType mime_type) {
   ad_network_bytes_ += unaccounted_ad_bytes;
   ad_bytes_ += unaccounted_ad_bytes;
-
-  if (mime_type == ResourceMimeType::kVideo)
-    ad_video_network_bytes_ += unaccounted_ad_bytes;
-  else if (mime_type == ResourceMimeType::kJavascript)
-    ad_javascript_network_bytes_ += unaccounted_ad_bytes;
+  ad_bytes_by_mime_[static_cast<size_t>(mime_type)] += unaccounted_ad_bytes;
 }
 
 void FrameData::SetFrameSize(gfx::Size frame_size) {
@@ -162,6 +155,10 @@ void FrameData::SetReceivedUserActivation(base::TimeDelta foreground_duration) {
   pre_activation_foreground_duration_ = foreground_duration;
 }
 
+size_t FrameData::GetAdNetworkBytesForMime(ResourceMimeType mime_type) const {
+  return ad_bytes_by_mime_[static_cast<size_t>(mime_type)];
+}
+
 void FrameData::UpdateFrameVisibility() {
   visibility_ =
       !is_display_none_ &&

chrome/browser/page_load_metrics/observers/ad_metrics/frame_data.h

@@ -145,11 +145,7 @@ class FrameData {
 
   size_t ad_network_bytes() const { return ad_network_bytes_; }
 
-  size_t ad_video_network_bytes() const { return ad_video_network_bytes_; }
-
-  size_t ad_javascript_network_bytes() const {
-    return ad_javascript_network_bytes_;
-  }
+  size_t GetAdNetworkBytesForMime(ResourceMimeType mime_type) const;
 
   UserActivationStatus user_activation_status() const {
     return user_activation_status_;
@@ -179,10 +175,10 @@ class FrameData {
   size_t bytes_;
   size_t network_bytes_;
 
-  // Tallies for bytes and counts observed in resource data updates for the
+  // Records ad network bytes for different mime type resources loaded in the
   // frame.
-  size_t ad_javascript_network_bytes_ = 0u;
-  size_t ad_video_network_bytes_ = 0u;
+  size_t ad_bytes_by_mime_[static_cast<size_t>(ResourceMimeType::kMaxValue) +
+                           1] = {0};
 
   // Time spent by the frame in the cpu before and after interactive.
   base::TimeDelta cpu_by_interactive_period_[static_cast<size_t>(