Bug 1865845: refactor attribution code to clearly separate out flows for mac, nsis, and msix r=nalexander

This function has been difficult to read for awhile. This patch cleans it up in preparation to adjust it for the removal of the cache file on macOS.

Differential Revision: https://phabricator.services.mozilla.com/D197203

Author: bhearsum

browser/components/attribution/AttributionCode.sys.mjs

@@ -227,6 +227,76 @@ export var AttributionCode = {
     return s;
   },
 
+  async _getMacAttrDataAsync() {
+    let attributionFile = this.attributionFile;
+
+    // On macOS, we fish the attribution data from an extended attribute on
+    // the .app bundle directory.
+    try {
+      let attrStr = await lazy.MacAttribution.getAttributionString();
+      lazy.log.debug(
+        `getAttrDataAsync: macOS attribution getAttributionString: "${attrStr}"`
+      );
+
+      gCachedAttrData = this.parseAttributionCode(attrStr);
+    } catch (ex) {
+      // Avoid partial attribution data.
+      gCachedAttrData = {};
+
+      // No attributions.  Just `warn` 'cuz this isn't necessarily an error.
+      lazy.log.warn("Caught exception fetching macOS attribution codes!", ex);
+
+      if (
+        ex instanceof Ci.nsIException &&
+        ex.result == Cr.NS_ERROR_UNEXPECTED
+      ) {
+        // Bad quarantine data.
+        Services.telemetry
+          .getHistogramById("BROWSER_ATTRIBUTION_ERRORS")
+          .add("quarantine_error");
+      }
+    }
+
+    lazy.log.debug(
+      `macOS attribution data is ${JSON.stringify(gCachedAttrData)}`
+    );
+
+    // We only want to try to fetch the attribution string once on macOS
+    try {
+      let code = this.serializeAttributionData(gCachedAttrData);
+      lazy.log.debug(`macOS attribution data serializes as "${code}"`);
+      await this.writeAttributionFile(code);
+    } catch (ex) {
+      lazy.log.debug(`Caught exception writing "${attributionFile.path}"`, ex);
+      Services.telemetry
+        .getHistogramById("BROWSER_ATTRIBUTION_ERRORS")
+        .add("write_error");
+      return gCachedAttrData;
+    }
+
+    lazy.log.debug(
+      `Returning after successfully writing "${attributionFile.path}"`
+    );
+    return gCachedAttrData;
+  },
+
+  async _getWindowsNSISAttrDataAsync() {
+    return AttributionIOUtils.read(this.attributionFile.path);
+  },
+
+  async _getWindowsMSIXAttrDataAsync() {
+    // This comes out of windows-package-manager _not_ URL encoded or in an ArrayBuffer,
+    // but the parsing code wants it that way. It's easier to just provide that
+    // than have the parsing code support both.
+    lazy.log.debug(
+      `winPackageFamilyName is: ${Services.sysinfo.getProperty(
+        "winPackageFamilyName"
+      )}`
+    );
+    let encoder = new TextEncoder();
+    return encoder.encode(encodeURIComponent(await this.msixCampaignId()));
+  },
+
   /**
    * Reads the attribution code, either from disk or a cached version.
    * Returns a promise that fulfills with an object containing the parsed
@@ -275,58 +345,7 @@ export var AttributionCode = {
       lazy.log.debug(
         `getAttrDataAsync: macOS && !exists("${attributionFile.path}")`
       );
-
-      // On macOS, we fish the attribution data from an extended attribute on
-      // the .app bundle directory.
-      try {
-        let attrStr = await lazy.MacAttribution.getAttributionString();
-        lazy.log.debug(
-          `getAttrDataAsync: macOS attribution getAttributionString: "${attrStr}"`
-        );
-
-        gCachedAttrData = this.parseAttributionCode(attrStr);
-      } catch (ex) {
-        // Avoid partial attribution data.
-        gCachedAttrData = {};
-
-        // No attributions.  Just `warn` 'cuz this isn't necessarily an error.
-        lazy.log.warn("Caught exception fetching macOS attribution codes!", ex);
-
-        if (
-          ex instanceof Ci.nsIException &&
-          ex.result == Cr.NS_ERROR_UNEXPECTED
-        ) {
-          // Bad quarantine data.
-          Services.telemetry
-            .getHistogramById("BROWSER_ATTRIBUTION_ERRORS")
-            .add("quarantine_error");
-        }
-      }
-
-      lazy.log.debug(
-        `macOS attribution data is ${JSON.stringify(gCachedAttrData)}`
-      );
-
-      // We only want to try to fetch the attribution string once on macOS
-      try {
-        let code = this.serializeAttributionData(gCachedAttrData);
-        lazy.log.debug(`macOS attribution data serializes as "${code}"`);
-        await this.writeAttributionFile(code);
-      } catch (ex) {
-        lazy.log.debug(
-          `Caught exception writing "${attributionFile.path}"`,
-          ex
-        );
-        Services.telemetry
-          .getHistogramById("BROWSER_ATTRIBUTION_ERRORS")
-          .add("write_error");
-        return gCachedAttrData;
-      }
-
-      lazy.log.debug(
-        `Returning after successfully writing "${attributionFile.path}"`
-      );
-      return gCachedAttrData;
+      return this._getMacAttrDataAsync();
     }
 
     lazy.log.debug(
@@ -339,18 +358,9 @@ export var AttributionCode = {
         AppConstants.platform === "win" &&
         Services.sysinfo.getProperty("hasWinPackageId")
       ) {
-        // This comes out of windows-package-manager _not_ URL encoded or in an ArrayBuffer,
-        // but the parsing code wants it that way. It's easier to just provide that
-        // than have the parsing code support both.
-        lazy.log.debug(
-          `winPackageFamilyName is: ${Services.sysinfo.getProperty(
-            "winPackageFamilyName"
-          )}`
-        );
-        let encoder = new TextEncoder();
-        bytes = encoder.encode(encodeURIComponent(await this.msixCampaignId()));
+        bytes = await this._getWindowsMSIXAttrDataAsync();
       } else {
-        bytes = await AttributionIOUtils.read(attributionFile.path);
+        bytes = await this._getWindowsNSISAttrDataAsync();
       }
     } catch (ex) {
       if (DOMException.isInstance(ex) && ex.name == "NotFoundError") {