Refactor Histogram relationship diagnostics.

tracing/tracing/metrics/system_health/memory_metric.html

Index: tracing/tracing/metrics/system_health/memory_metric.html
diff --git a/tracing/tracing/metrics/system_health/memory_metric.html b/tracing/tracing/metrics/system_health/memory_metric.html
index 3000abbdb5770d4121e7961319805438368ce6cf..ee7eda13e0b7c2f5d05b1aa1fdba571de5a119c1 100644
--- a/tracing/tracing/metrics/system_health/memory_metric.html
+++ b/tracing/tracing/metrics/system_health/memory_metric.html
@@ -1089,7 +1089,7 @@ tr.exportTo('tr.metrics.sh', function() {
    * (corresponding to global memory dumps associated with the given browser)
    * |values| for each process (e.g. 'gpu_process', 'browser_process', etc).
    * We also report a special 'all_processes' histogram which agregates all
-   * others, this has a RelatedHistogramBreakdown diagnostic explaining
+   * others, this has a RelatedNameMap diagnostic explaining
    * how it is built from the other histograms.
    *
    * See addMemoryDumpValues for more details.
@@ -1121,32 +1121,30 @@ tr.exportTo('tr.metrics.sh', function() {
     }
     cachedHistograms.set(histogram.name, histogram);
 
-    const processBreakdown = new tr.v.d.RelatedHistogramBreakdown();
-    processBreakdown.colorScheme =
-      tr.e.chrome.chrome_processes.PROCESS_COLOR_SCHEME_NAME;
+    const processNames = new tr.v.d.RelatedNameMap();
     for (const [childProcessName, childProcessNode] of tree.children[0]) {
       processPath.push(childProcessName);
       const childProcessHistogram =
         recurse(processPath, componentPath, childProcessNode);
-      processBreakdown.set(childProcessName, childProcessHistogram);
+      processNames.set(childProcessName, childProcessHistogram.name);
       processPath.pop();
     }
 
-    const componentBreakdown = new tr.v.d.RelatedHistogramBreakdown();
+    const componentNames = new tr.v.d.RelatedNameMap();
     for (const [childComponentName, childComponentNode] of tree.children[1]) {
       componentPath.push(childComponentName);
       const childComponentHistogram =
         recurse(processPath, componentPath, childComponentNode);
-      componentBreakdown.set(childComponentName, childComponentHistogram);
+      componentNames.set(childComponentName, childComponentHistogram.name);
       componentPath.pop();
     }
 
     values.addHistogram(histogram);
     if (tree.children[0].size > 0) {
-      histogram.diagnostics.set('processes', processBreakdown);
+      histogram.diagnostics.set('processes', processNames);
     }
     if (tree.children[1].size > 0) {
-      histogram.diagnostics.set('components', componentBreakdown);
+      histogram.diagnostics.set('components', componentNames);
     }
 
     return histogram;
@@ -1198,6 +1196,33 @@ tr.exportTo('tr.metrics.sh', function() {
     return numeric;
   }
 
+  function buildSampleDiagnostics(value, node) {
+    if (node.children.length < 2) return undefined;
+    const diagnostics = new Map();
+    const i = node.values.indexOf(value);
+
+    const processBreakdown = new tr.v.d.Breakdown();
+    processBreakdown.colorScheme =
+      tr.e.chrome.chrome_processes.PROCESS_COLOR_SCHEME_NAME;
+    for (const [name, subNode] of node.children[0]) {
+      processBreakdown.set(name, subNode.values[i].total);
+    }
+    if (processBreakdown.size > 0) {
+      diagnostics.set('processes', processBreakdown);
+    }
+
+    const componentBreakdown = new tr.v.d.Breakdown();
+    for (const [name, subNode] of node.children[1]) {
+      componentBreakdown.set(name, subNode.values[i].total);
+    }
+    if (componentBreakdown.size > 0) {
+      diagnostics.set('components', componentBreakdown);
+    }
+
+    if (diagnostics.size === 0) return undefined;
+    return diagnostics;
+  }
+
   /**
    * Create a memory tr.v.Histogram with |unit| and add all total values in
    * |node| to it.
@@ -1205,7 +1230,10 @@ tr.exportTo('tr.metrics.sh', function() {
   function buildMemoryNumericFromNode(name, node, unit) {
     const histogram = new tr.v.Histogram(
         name, unit, BOUNDARIES_FOR_UNIT_MAP.get(unit));
-    node.values.forEach(v => histogram.addSample(v.total));
+
+    node.values.forEach(v => histogram.addSample(
+        v.total, buildSampleDiagnostics(v, node)));
+
     return histogram;
   }