Reorder misplaced <histogram> and <histogram_suffixes>

Ensure that <histogram> should be added in <hisotgrams> and
<histogram_suffixes> should be added in <histogram_suffixes_list> so
that they will be sorted separately.

Bug: 1034123
Change-Id: Iaf009dacf20a549f6e5865a4a699bb3919e96082
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1978539
Commit-Queue: Weilun Shi <sweilun@chromium.org>
Reviewed-by: Ilya Sherman <isherman@chromium.org>
Cr-Commit-Position: refs/heads/master@{#728635}

tools/metrics/histograms/pretty_print.py

@@ -75,19 +75,57 @@ def fixObsoleteOrder(tree):
   if obsoletes:
     tree.insert(0, obsoletes[0])
 
-def DropNodesByTagName(tree, tag):
+def DropNodesByTagName(tree, tag, dropped_nodes=[]):
   """Drop all nodes with named tag from the XML tree."""
   removes = []
 
   for child in tree:
     if child.tag == tag:
       removes.append(child)
+      dropped_nodes.append(child)
     else:
       DropNodesByTagName(child, tag)
 
   for child in removes:
     tree.remove(child)
 
+def FixMisplacedHistogramsAndHistogramSuffixes(tree):
+  """Fixes misplaced histogram and histogram_suffixes nodes."""
+  histograms = []
+  histogram_suffixes = []
+
+  def ExtractMisplacedHistograms(tree):
+    """Gets and drops misplaced histograms and histogram_suffixes.
+
+    Args:
+      tree: The node of the xml tree.
+      histograms: A list of histogram nodes inside histogram_suffixes_list
+          node. This is a return element.
+      histogram_suffixes: A list of histogram_suffixes nodes inside hisotgrams
+          node. This is a return element.
+    """
+    for child in tree:
+      if child.tag == 'histograms':
+        DropNodesByTagName(child, 'histogram_suffixes', histogram_suffixes)
+      elif child.tag == 'histogram_suffixes_list':
+        DropNodesByTagName(child, 'histogram', histograms)
+      else:
+        ExtractMisplacedHistograms(child)
+
+  ExtractMisplacedHistograms(tree)
+
+  def AddBackMisplacedHisotgrams(tree):
+    """Adds back those misplaced histogram and hsitogram_suffixes nodes."""
+    for child in tree:
+      if child.tag == 'histograms':
+        child.extend(histograms)
+      elif child.tag == 'histogram_suffixes_list':
+        child.extend(histogram_suffixes)
+      else:
+        FixMisplacedHisotgrams(child)
+
+  AddBackMisplacedHisotgrams(tree)
+
 def PrettyPrintHistograms(raw_xml):
   """Pretty-print the given histograms XML.
 
@@ -112,6 +150,7 @@ def PrettyPrintHistogramsTree(tree):
   """
   # Prevent accidentally adding enums to histograms.xml
   DropNodesByTagName(tree, 'enums')
+  FixMisplacedHistogramsAndHistogramSuffixes(tree)
   canonicalizeUnits(tree)
   fixObsoleteOrder(tree)
   return histograms_print_style.GetPrintStyle().PrettyPrintXml(tree)

tools/metrics/histograms/pretty_print_test.py

@@ -25,6 +25,7 @@ ORIGINAL_XML = """
        Removed 1/2019.
    </obsolete>
  </histogram>
+
  <histogram name="Foo.Bar" units="xxxxxxxxxxxxxxxxxxyyyyyyyyyyyyyyyyyyyyyyzzzz">
   <summary>Foo</summary>
   <obsolete>Obsolete 1</obsolete>
@@ -33,12 +34,29 @@ ORIGINAL_XML = """
   <component>Component</component>
   <component>Other&gt;Component</component>
  </histogram>
+
+ <histogram_suffixes name="Test.HistogramSuffixes" separator=".">
+  <suffix name="TestSuffix" label="A misplaced histogram_suffixes"/>
+  <affected-histogram name="Test.Histogram"/>
+</histogram_suffixes>
+
 </histograms>
+
+<histogram_suffixes_list>
+
+<histogram name="Test.MisplacedHistogram" units="us">
+   <owner>person@chromium.org</owner>
+   <summary>A misplaced histogram
+   </summary>
+   Misplaced content.
+ </histogram>
+
+</histogram_suffixes_list>
+
 <enums>This shouldn't be here</enums>
 </histogram-configuration>
 """.strip()
 
-
 PRETTY_XML = """
 <!-- Top level Comment 1 -->
 <!-- Top level Comment 2 -->
@@ -70,8 +88,23 @@ PRETTY_XML = """
   Mixed content.
 </histogram>
 
+<histogram name="Test.MisplacedHistogram" units="microseconds">
+  <owner>person@chromium.org</owner>
+  <summary>A misplaced histogram</summary>
+  Misplaced content.
+</histogram>
+
 </histograms>
 
+<histogram_suffixes_list>
+
+<histogram_suffixes name="Test.HistogramSuffixes" separator=".">
+  <suffix name="TestSuffix" label="A misplaced histogram_suffixes"/>
+  <affected-histogram name="Test.Histogram"/>
+</histogram_suffixes>
+
+</histogram_suffixes_list>
+
 </histogram-configuration>
 """.strip()