Read feature param for Physical Web experiment

chrome/android/java/src/org/chromium/chrome/browser/physicalweb/PhysicalWeb.java

Index: chrome/android/java/src/org/chromium/chrome/browser/physicalweb/PhysicalWeb.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/physicalweb/PhysicalWeb.java b/chrome/android/java/src/org/chromium/chrome/browser/physicalweb/PhysicalWeb.java
index 5923cfea421d2c57cb47ba2de2e224d4a1cc1516..f89a20d25f0721a8bac1d71c5e0213b3912ddc3d 100644
--- a/chrome/android/java/src/org/chromium/chrome/browser/physicalweb/PhysicalWeb.java
+++ b/chrome/android/java/src/org/chromium/chrome/browser/physicalweb/PhysicalWeb.java
@@ -16,17 +16,23 @@ import org.chromium.chrome.browser.ChromeVersionInfo;
  * This class provides the basic interface to the Physical Web feature.
  */
 public class PhysicalWeb {
+    private static final String FIELD_TRIAL_NAME = "PhysicalWeb";
+    private static final String ENABLED_PARAM = "enabled";
+    private static final String ENABLED_VALUE = "true";
+
     /**
      * Evaluate whether the environment is one in which the Physical Web should
      * be enabled.
      * @return true if the PhysicalWeb should be enabled
      */
     public static boolean featureIsEnabled() {
+        // TODO(cco3): Remove chrome://flag after Finch is experiment is more in place.

[mmocny, 2015/12/10 15:07:04]

I thought we still want to make the chrome://flag available to allow explicit
opt-in?

[cco3, 2015/12/11 21:32:19]

That's what I thought too, but this seriously complicates things because it's
not clear whether the flag was turned off intentionally as a hard signal that
the feature is to be turned off.  Matt might be able to comment further since
he's been working with this logic.

People can still turn it on with a command line flag though.

         boolean allowedChannel =
                 ChromeVersionInfo.isLocalBuild() || ChromeVersionInfo.isDevBuild();
         boolean switchEnabled =
                 CommandLine.getInstance().hasSwitch(ChromeSwitches.ENABLE_PHYSICAL_WEB);
-        return allowedChannel && switchEnabled;
+        // Check chrome://flag, command line flag, and finch, in that order
+        return (allowedChannel && switchEnabled) || getBooleanParam(ENABLED_PARAM);
     }
 
     /**
@@ -70,4 +76,20 @@ public class PhysicalWeb {
         };
         AsyncTask.THREAD_POOL_EXECUTOR.execute(task);
     }
+
+    /**
+     * Gets a boolean Finch parameter, assuming the <paramName>="true" format.  Also checks for a
+     * command-line switch with the same name, for easy local testing.
+     * @param paramName The name of the Finch parameter (or command-line switch) to get a value for.
+     * @param defaultValue The default value to return when there's no param or switch.
+     * @return Whether the Finch param is defined with a value "true", if there's a command-line
+     *         flag present with any value.
+     */
+    private static boolean getBooleanParam(String paramName, boolean defaultValue) {

[nyquist, 2015/12/10 00:04:06]

defaultValue doesn't seem to be used? In the call above you don't seem to be
passing it either. Did you try compiling this?

[cco3, 2015/12/10 01:22:54]

Done.

+        if (CommandLine.getInstance().hasSwitch(paramName)) {
+            return true;
+        }
+        return TextUtils.equals(ENABLED_VALUE,
+                VariationsAssociatedData.getVariationParamValue(FIELD_TRIAL_NAME, paramName));
+    }
 }