web-install: Implement Android reconnection callback

On Android, Chromium does not support automatic reconnection. The user
must manually pair the device after every reboot in order for
fastboot.js to reconnect to it. Unfortunately, this requires the user of
the library to get involved because USB device connction requests are
only allowed as the result of explicit user action, so we need to add a
reconnect request callback for the user to handle.

2 files changed, 26 insertions, 6 deletions

diff --git a/static/install/web.html b/static/install/web.html
index dc04ad3a..0ee9ea82 100644
--- a/static/install/web.html
+++ b/static/install/web.html
@@ -179,7 +179,11 @@
                 Then, proceed to <a href="#locking-the-bootloader">locking the bootloader</a>
                 before using the device as locking wipes the data again.</p>
 
-                <p><strong id="flash-release-status"></strong></p>
+                <p>
+                    <strong id="flash-release-status"></strong>
+                    <!-- This appears as part of the status -->
+                    <button id="flash-reconnect-button" style="display: none;"><strong>Reconnect device</strong></button>
+                </p>
             </section>
 
             <section id="locking-the-bootloader">
diff --git a/static/js/web-install.js b/static/js/web-install.js
index ed8c9fd2..660fd02e 100644
--- a/static/js/web-install.js
+++ b/static/js/web-install.js
@@ -148,6 +148,19 @@ async function downloadRelease(setProgress) {
     return `Downloaded ${latestZip} release.`;
 }
 
+async function reconnectCallback() {
+    let statusField = document.getElementById("flash-release-status");
+    statusField.textContent =
+        "In order to continue flashing, you need to reconnect the device by tapping here:";
+
+    let reconnectButton = document.getElementById("flash-reconnect-button");
+    reconnectButton.style.display = "inline-block";
+    reconnectButton.onclick = async () => {
+        await device.connect();
+        reconnectButton.style.display = "none";
+    };
+}
+
 async function flashRelease(setProgress) {
     await ensureConnected(setProgress);
 
@@ -162,11 +175,14 @@ async function flashRelease(setProgress) {
     }
 
     setProgress("Flashing release...");
-    await fastboot.FactoryImages.flashZip(device, blob, true, (action, item) => {
-        let userAction = fastboot.FactoryImages.USER_ACTION_MAP[action];
-        let userItem = item === "avb_custom_key" ? "verified boot key" : item;
-        setProgress(`${userAction} ${userItem}...`);
-    });
+    await fastboot.FactoryImages.flashZip(
+        device, blob, true, reconnectCallback,
+        (action, item) => {
+            let userAction = fastboot.FactoryImages.USER_ACTION_MAP[action];
+            let userItem = item === "avb_custom_key" ? "verified boot key" : item;
+            setProgress(`${userAction} ${userItem}...`);
+        }
+    );
 
     return `Flashed ${latestZip} to device.`;
 }