Add a section to Site Settings listing USB devices.

chrome/android/java/src/org/chromium/chrome/browser/preferences/website/UsbInfo.java

Index: chrome/android/java/src/org/chromium/chrome/browser/preferences/website/UsbInfo.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/preferences/website/UsbInfo.java b/chrome/android/java/src/org/chromium/chrome/browser/preferences/website/UsbInfo.java
index c48aa1e67453b2924b4b259831a54ea7e39d0edf..3da87b4e23bacfa05deee52f5584c6a129434c6b 100644
--- a/chrome/android/java/src/org/chromium/chrome/browser/preferences/website/UsbInfo.java
+++ b/chrome/android/java/src/org/chromium/chrome/browser/preferences/website/UsbInfo.java
@@ -8,6 +8,9 @@ import java.io.Serializable;
 
 /**
  * USB device information for a given origin.
+ *
+ * These objects are compared only by the identity of the device, not by which site has permission
+ * to access it.
  */
 public class UsbInfo implements Serializable {
     private final String mOrigin;
@@ -49,4 +52,18 @@ public class UsbInfo implements Serializable {
     public void revoke() {
         WebsitePreferenceBridge.nativeRevokeUsbPermission(mOrigin, mEmbedder, mObject);
     }
+
+    @Override
+    public int hashCode() {
+        return mObject.hashCode();

[Ted C, 2016/08/15 20:31:59]

I find this to be somewhat odd.

Why not just expose mObject and use that for the key in your maps?  This just
seems like you are special casing this behavior to one implementation in the UI
and that seems fragile.

If we keep this as is, I think we should write some simple tests that force this
behavior to be maintained as I don't think the comment above would be sufficient
for people to realize the implications of changing it.

[Reilly Grant (use Gerrit), 2016/08/16 17:41:59]

Good idea, done.

+    }
+
+    @Override
+    public boolean equals(Object obj) {
+        if (obj instanceof UsbInfo) {
+            UsbInfo other = (UsbInfo) obj;
+            return mObject.equals(other.mObject);
+        }
+        return false;
+    }
 }