[LazyParseCSS] Add metrics for total # of rules at 0% and 100% usage

third_party/WebKit/Source/core/css/parser/CSSLazyParsingTest.cpp

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "core/css/CSSStyleSheet.h"
 #include "core/css/StyleRule.h"
 #include "core/css/StyleSheetContents.h"
 #include "core/css/parser/CSSLazyParsingState.h"
 #include "core/css/parser/CSSParser.h"
 #include "core/css/parser/CSSParserContext.h"
@@ skipping 155 matching lines @@
   UseCounter& useCounter2 = dummyHolder2->document().frameHost()->useCounter();
   EXPECT_TRUE(sheet2);
   EXPECT_TRUE(useCounter2.isCounted(CSSPropertyColor));
   EXPECT_FALSE(useCounter2.isCounted(CSSPropertyBackgroundColor));
 }
 
 TEST_F(CSSLazyParsingTest, SimpleRuleUsagePercent) {
   CSSParserContext* context = CSSParserContext::create(HTMLStandardMode);
   StyleSheetContents* styleSheet = StyleSheetContents::create(context);
 
-  std::string metricName = "Style.LazyUsage.Percent";
-  m_histogramTester.expectTotalCount(metricName, 0);
+  std::string usageMetric = "Style.LazyUsage.Percent";
+  std::string totalRulesMetric = "Style.TotalLazyRules";
+  std::string totalRulesFullUsageMetric = "Style.TotalLazyRules.FullUsage";
+  m_histogramTester.expectTotalCount(usageMetric, 0);
 
   String sheetText =
       "body { background-color: red; }"
       "p { color: blue; }"
       "a { color: yellow; }"
       "#id { color: blue; }"
       "div { color: grey; }";
   CSSParser::parseSheet(context, styleSheet, sheetText, true /* lazy parse */);
 
-  m_histogramTester.expectTotalCount(metricName, 1);
-  m_histogramTester.expectUniqueSample(metricName,
+  m_histogramTester.expectTotalCount(totalRulesMetric, 1);
+  m_histogramTester.expectUniqueSample(totalRulesMetric, 5, 1);
+
+  // Only log the full usage metric when all the rules have been actually
+  // parsed.
+  m_histogramTester.expectTotalCount(totalRulesFullUsageMetric, 0);
+
+  m_histogramTester.expectTotalCount(usageMetric, 1);
+  m_histogramTester.expectUniqueSample(usageMetric,
                                        CSSLazyParsingState::UsageGe0, 1);
 
   ruleAt(styleSheet, 0)->properties();
-  m_histogramTester.expectTotalCount(metricName, 2);
-  m_histogramTester.expectBucketCount(metricName,
+  m_histogramTester.expectTotalCount(usageMetric, 2);
+  m_histogramTester.expectBucketCount(usageMetric,
                                       CSSLazyParsingState::UsageGt10, 1);
 
   ruleAt(styleSheet, 1)->properties();
-  m_histogramTester.expectTotalCount(metricName, 3);
-  m_histogramTester.expectBucketCount(metricName,
+  m_histogramTester.expectTotalCount(usageMetric, 3);
+  m_histogramTester.expectBucketCount(usageMetric,
                                       CSSLazyParsingState::UsageGt25, 1);
 
   ruleAt(styleSheet, 2)->properties();
-  m_histogramTester.expectTotalCount(metricName, 4);
-  m_histogramTester.expectBucketCount(metricName,
+  m_histogramTester.expectTotalCount(usageMetric, 4);
+  m_histogramTester.expectBucketCount(usageMetric,
                                       CSSLazyParsingState::UsageGt50, 1);
 
   ruleAt(styleSheet, 3)->properties();
-  m_histogramTester.expectTotalCount(metricName, 5);
-  m_histogramTester.expectBucketCount(metricName,
+  m_histogramTester.expectTotalCount(usageMetric, 5);
+  m_histogramTester.expectBucketCount(usageMetric,
                                       CSSLazyParsingState::UsageGt75, 1);
 
+  // Only log the full usage metric when all the rules have been actually
+  // parsed.
+  m_histogramTester.expectTotalCount(totalRulesFullUsageMetric, 0);
+
   // Parsing the last rule bumps both Gt90 and All buckets.
   ruleAt(styleSheet, 4)->properties();
-  m_histogramTester.expectTotalCount(metricName, 7);
-  m_histogramTester.expectBucketCount(metricName,
+  m_histogramTester.expectTotalCount(usageMetric, 7);
+  m_histogramTester.expectBucketCount(usageMetric,
                                       CSSLazyParsingState::UsageGt90, 1);
-  m_histogramTester.expectBucketCount(metricName, CSSLazyParsingState::UsageAll,
-                                      1);
+  m_histogramTester.expectBucketCount(usageMetric,
+                                      CSSLazyParsingState::UsageAll, 1);
+
+  m_histogramTester.expectTotalCount(totalRulesFullUsageMetric, 1);
+  m_histogramTester.expectUniqueSample(totalRulesFullUsageMetric, 5, 1);
 }
 
 }  // namespace blink