Adding PLM UMA for byte usage by load type

chrome/browser/page_load_metrics/observers/core_page_load_metrics_observer.cc

Index: chrome/browser/page_load_metrics/observers/core_page_load_metrics_observer.cc
diff --git a/chrome/browser/page_load_metrics/observers/core_page_load_metrics_observer.cc b/chrome/browser/page_load_metrics/observers/core_page_load_metrics_observer.cc
index 14d1318e9080afb7bb2491b718997df148c8367f..2ecce01554539e91d8b92435803fdcef96589e75 100644
--- a/chrome/browser/page_load_metrics/observers/core_page_load_metrics_observer.cc
+++ b/chrome/browser/page_load_metrics/observers/core_page_load_metrics_observer.cc
@@ -222,6 +222,27 @@ const char kHistogramTotalBytes[] = "PageLoad.Experimental.Bytes.Total";
 const char kHistogramNetworkBytes[] = "PageLoad.Experimental.Bytes.Network";
 const char kHistogramCacheBytes[] = "PageLoad.Experimental.Bytes.Cache";
 
+const char kHistogramLoadTypeTotalBytesForwardBack[] =
+    "PageLoad.Experimental.Bytes.Total.LoadType.ForwardBackNavigation";
+const char kHistogramLoadTypeNetworkBytesForwardBack[] =
+    "PageLoad.Experimental.Bytes.Network.LoadType.ForwardBackNavigation";
+const char kHistogramLoadTypeCacheBytesForwardBack[] =
+    "PageLoad.Experimental.Bytes.Cache.LoadType.ForwardBackNavigation";
+
+const char kHistogramLoadTypeTotalBytesReload[] =
+    "PageLoad.Experimental.Bytes.Total.LoadType.Reload";
+const char kHistogramLoadTypeNetworkBytesReload[] =
+    "PageLoad.Experimental.Bytes.Network.LoadType.Reload";
+const char kHistogramLoadTypeCacheBytesReload[] =
+    "PageLoad.Experimental.Bytes.Cache.LoadType.Reload";
+
+const char kHistogramLoadTypeTotalBytesNewNavigation[] =
+    "PageLoad.Experimental.Bytes.Total.LoadType.NewNavigation";
+const char kHistogramLoadTypeNetworkBytesNewNavigation[] =
+    "PageLoad.Experimental.Bytes.Network.LoadType.NewNavigation";
+const char kHistogramLoadTypeCacheBytesNewNavigation[] =
+    "PageLoad.Experimental.Bytes.Cache.LoadType.NewNavigation";
+
 const char kHistogramTotalCompletedResources[] =
     "PageLoad.Experimental.CompletedResources.Total";
 const char kHistogramNetworkCompletedResources[] =
@@ -728,6 +749,37 @@ void CorePageLoadMetricsObserver::RecordByteAndResourceHistograms(
   PAGE_BYTES_HISTOGRAM(internal::kHistogramCacheBytes, cache_bytes_);
   PAGE_BYTES_HISTOGRAM(internal::kHistogramTotalBytes, total_bytes);
 
+  switch (GetPageLoadType(transition_)) {

[bengr, 2017/03/01 20:54:13]

Are there any other transitions of interest? Ideally, e.g., a transition to load
an original page after a preview should be a transition type. Consider adding a
TODO with a crbug for previews.

+    case LOAD_TYPE_RELOAD:
+      PAGE_BYTES_HISTOGRAM(internal::kHistogramLoadTypeNetworkBytesReload,
+                           network_bytes_);
+      PAGE_BYTES_HISTOGRAM(internal::kHistogramLoadTypeCacheBytesReload,
+                           cache_bytes_);
+      PAGE_BYTES_HISTOGRAM(internal::kHistogramLoadTypeTotalBytesReload,
+                           total_bytes);
+      break;
+    case LOAD_TYPE_FORWARD_BACK:
+      PAGE_BYTES_HISTOGRAM(internal::kHistogramLoadTypeNetworkBytesForwardBack,
+                           network_bytes_);
+      PAGE_BYTES_HISTOGRAM(internal::kHistogramLoadTypeCacheBytesForwardBack,
+                           cache_bytes_);
+      PAGE_BYTES_HISTOGRAM(internal::kHistogramLoadTypeTotalBytesForwardBack,
+                           total_bytes);
+      break;
+    case LOAD_TYPE_NEW_NAVIGATION:
+      PAGE_BYTES_HISTOGRAM(
+          internal::kHistogramLoadTypeNetworkBytesNewNavigation,
+          network_bytes_);
+      PAGE_BYTES_HISTOGRAM(internal::kHistogramLoadTypeCacheBytesNewNavigation,
+                           cache_bytes_);
+      PAGE_BYTES_HISTOGRAM(internal::kHistogramLoadTypeTotalBytesNewNavigation,
+                           total_bytes);
+      break;
+    case LOAD_TYPE_NONE:
+      NOTREACHED();
+      break;
+  }
+
   PAGE_RESOURCE_COUNT_HISTOGRAM(internal::kHistogramNetworkCompletedResources,
                                 num_network_resources_);
   PAGE_RESOURCE_COUNT_HISTOGRAM(internal::kHistogramCacheCompletedResources,