Add ConversionMeasurement attributes to anchor tag IDL

What: Add impression attributes to anchor element IDL, gated behind
the ConversionMeasurement.

Why: We want to allow programmatic assignment of conversion measurement
without having to use SetAttribute for simplicity.

API explainer: https://github.com/WICG/conversion-measurement-api

Bug: 1097144
Change-Id: I58a40998642aee5e7ae3f632c95a531604c93ea1
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2258254
Commit-Queue: John Delaney <johnidel@chromium.org>
Reviewed-by: Charlie Harrison <csharrison@chromium.org>
Reviewed-by: Nate Chapin <japhet@chromium.org>
Cr-Commit-Position: refs/heads/master@{#795776}

third_party/blink/renderer/core/html/html_anchor_element.idl

@@ -35,6 +35,12 @@
 
     [CEReactions, ImplementedAs=textContent] attribute DOMString text;
 
+    // Conversion Measurement
+    [RuntimeEnabled=ConversionMeasurement, CEReactions,Reflect] attribute DOMString impressionData;
+    [RuntimeEnabled=ConversionMeasurement, CEReactions,Reflect] attribute USVString conversionDestination;
+    [RuntimeEnabled=ConversionMeasurement, CEReactions,Reflect] attribute USVString reportingOrigin;
+    [RuntimeEnabled=ConversionMeasurement, CEReactions,Reflect] attribute DOMString impressionExpiry;
+
     // obsolete members
     // https://html.spec.whatwg.org/C/#HTMLAnchorElement-partial
     [CEReactions, Reflect] attribute DOMString coords;

third_party/blink/web_tests/webexposed/element-instance-property-listing-expected.txt

@@ -325,6 +325,7 @@ namespace http://www.w3.org/1999/xhtml
     property webkitRequestFullscreen
 html element a
     property charset
+    property conversionDestination
     property coords
     property download
     property hash
@@ -333,6 +334,8 @@ html element a
     property href
     property hrefTranslate
     property hreflang
+    property impressionData
+    property impressionExpiry
     property name
     property origin
     property password
@@ -343,6 +346,7 @@ html element a
     property referrerPolicy
     property rel
     property relList
+    property reportingOrigin
     property rev
     property search
     property shape

third_party/blink/web_tests/webexposed/global-interface-listing-expected.txt

@@ -2685,6 +2685,7 @@ interface HTMLAllCollection
 interface HTMLAnchorElement : HTMLElement
     attribute @@toStringTag
     getter charset
+    getter conversionDestination
     getter coords
     getter download
     getter hash
@@ -2693,6 +2694,8 @@ interface HTMLAnchorElement : HTMLElement
     getter href
     getter hrefTranslate
     getter hreflang
+    getter impressionData
+    getter impressionExpiry
     getter name
     getter origin
     getter password
@@ -2703,6 +2706,7 @@ interface HTMLAnchorElement : HTMLElement
     getter referrerPolicy
     getter rel
     getter relList
+    getter reportingOrigin
     getter rev
     getter search
     getter shape
@@ -2713,6 +2717,7 @@ interface HTMLAnchorElement : HTMLElement
     method constructor
     method toString
     setter charset
+    setter conversionDestination
     setter coords
     setter download
     setter hash
@@ -2721,6 +2726,8 @@ interface HTMLAnchorElement : HTMLElement
     setter href
     setter hrefTranslate
     setter hreflang
+    setter impressionData
+    setter impressionExpiry
     setter name
     setter password
     setter pathname
@@ -2730,6 +2737,7 @@ interface HTMLAnchorElement : HTMLElement
     setter referrerPolicy
     setter rel
     setter relList
+    setter reportingOrigin
     setter rev
     setter search
     setter shape