Add UseCounters for effective usage of each of -webkit-user-modify values.

This is a follow-up CL of http://crrev.com/c/1335069.

Bug: 687843
Change-Id: I873dba8174a99c031e34f3e1f32672c6d275aea4
Reviewed-on: https://chromium-review.googlesource.com/c/1337143
Commit-Queue: Kent Tamura <tkent@chromium.org>
Reviewed-by: Yoshifumi Inoue <yosin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#609177}

third_party/blink/public/platform/web_feature.mojom

@@ -2087,6 +2087,9 @@ enum WebFeature {
   kLegacyTLSVersionInSubresource = 2635,
   kLegacyTLSVersionInSubframeMainResource = 2636,
   kRTCMaxAudioBufferSize = 2637,
+  kWebKitUserModifyReadWriteEffective = 2638,
+  kWebKitUserModifyReadOnlyEffective = 2639,
+  kWebKitUserModifyPlainTextEffective = 2640,
 
   // Add new features immediately above this line. Don't change assigned
   // numbers of any item, and don't reuse removed slots.

third_party/blink/renderer/core/dom/element.cc

@@ -178,22 +178,36 @@ bool IsRootEditableElementWithCounting(const Element& element) {
   const auto* style = element.GetComputedStyle();
   if (!style)
     return is_editable;
+  auto user_modify = style->UserModify();
   const AtomicString& ce_value = element.FastGetAttribute(kContenteditableAttr);
   if (ce_value.IsNull() || DeprecatedEqualIgnoringCase(ce_value, "false")) {
-    if (style->UserModify() != EUserModify::kReadOnly)
-      UseCounter::Count(doc, WebFeature::kWebKitUserModifyEffective);
-    if (style->UserModify() == EUserModify::kReadWritePlaintextOnly)
+    if (user_modify == EUserModify::kReadWritePlaintextOnly) {
       UseCounter::Count(doc, WebFeature::kPlainTextEditingEffective);
+      UseCounter::Count(doc, WebFeature::kWebKitUserModifyPlainTextEffective);
+      UseCounter::Count(doc, WebFeature::kWebKitUserModifyEffective);
+    } else if (user_modify == EUserModify::kReadWrite) {
+      UseCounter::Count(doc, WebFeature::kWebKitUserModifyReadWriteEffective);
+      UseCounter::Count(doc, WebFeature::kWebKitUserModifyEffective);
+    }
   } else if (ce_value.IsEmpty() ||
              DeprecatedEqualIgnoringCase(ce_value, "true")) {
-    if (style->UserModify() != EUserModify::kReadWrite)
-      UseCounter::Count(doc, WebFeature::kWebKitUserModifyEffective);
-    if (style->UserModify() == EUserModify::kReadWritePlaintextOnly)
+    if (user_modify == EUserModify::kReadWritePlaintextOnly) {
       UseCounter::Count(doc, WebFeature::kPlainTextEditingEffective);
-  } else if (DeprecatedEqualIgnoringCase(ce_value, "plaintext-only")) {
-    if (style->UserModify() != EUserModify::kReadWritePlaintextOnly)
+      UseCounter::Count(doc, WebFeature::kWebKitUserModifyPlainTextEffective);
       UseCounter::Count(doc, WebFeature::kWebKitUserModifyEffective);
+    } else if (user_modify == EUserModify::kReadOnly) {
+      UseCounter::Count(doc, WebFeature::kWebKitUserModifyReadOnlyEffective);
+      UseCounter::Count(doc, WebFeature::kWebKitUserModifyEffective);
+    }
+  } else if (DeprecatedEqualIgnoringCase(ce_value, "plaintext-only")) {
     UseCounter::Count(doc, WebFeature::kPlainTextEditingEffective);
+    if (user_modify == EUserModify::kReadWrite) {
+      UseCounter::Count(doc, WebFeature::kWebKitUserModifyReadWriteEffective);
+      UseCounter::Count(doc, WebFeature::kWebKitUserModifyEffective);
+    } else if (user_modify == EUserModify::kReadOnly) {
+      UseCounter::Count(doc, WebFeature::kWebKitUserModifyReadOnlyEffective);
+      UseCounter::Count(doc, WebFeature::kWebKitUserModifyEffective);
+    }
   }
   return is_editable;
 }

tools/metrics/histograms/enums.xml

@@ -20786,6 +20786,9 @@ Called by update_net_error_codes.py.-->
   <int value="2635" label="LegacyTLSVersionInSubresource"/>
   <int value="2636" label="LegacyTLSVersionInSubframeMainResource"/>
   <int value="2637" label="RTCMaxAudioBufferSize"/>
+  <int value="2638" label="WebKitUserModifyReadWriteEffective"/>
+  <int value="2639" label="WebKitUserModifyReadOnlyEffective"/>
+  <int value="2640" label="WebKitUserModifyPlainTextEffective"/>
 </enum>
 
 <enum name="FeaturePolicyFeature">