webauthn: allow GMSCore to trigger caBLEv2.

GMSCore is expected to start triggering caBLEv2, rather than doing
caBLEv1, for accounts.google.com logins. This change allows it to send
Intents to start Chrome to perform the caBLEv2 interaction.

BUG=1002262

Change-Id: I557f89d3bb191b738fe50e6a2377573a334fdb20
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2552623Reviewed-by: Andrew Grieve <agrieve@chromium.org>
Commit-Queue: Adam Langley <agl@chromium.org>
Cr-Commit-Position: refs/heads/master@{#829949}

chrome/android/expectations/monochrome_public_bundle.AndroidManifest.expected

@@ -599,9 +599,10 @@
       </intent-filter>  # DIFF-ANCHOR: 9c5197e9
     </activity>  # DIFF-ANCHOR: aea75380
     <activity  # DIFF-ANCHOR: a1fac31f
-        android:exported="false"
+        android:exported="true"
         android:label="@string/cablev2_activity_title"
         android:name="org.chromium.chrome.browser.webauth.authenticator.CableAuthenticatorActivity"
+        android:permission="com.google.android.gms.auth.cryptauth.permission.CABLEV2_SERVER_LINK"
         android:theme="@style/Theme.Chromium.Activity.Fullscreen">
       <intent-filter>  # DIFF-ANCHOR: 5873407a
         <action android:name="android.hardware.usb.action.USB_ACCESSORY_ATTACHED"/>

chrome/android/expectations/trichrome_chrome_bundle.AndroidManifest.expected

@@ -572,9 +572,10 @@
       </intent-filter>  # DIFF-ANCHOR: 9c5197e9
     </activity>  # DIFF-ANCHOR: aea75380
     <activity  # DIFF-ANCHOR: a1fac31f
-        android:exported="false"
+        android:exported="true"
         android:label="@string/cablev2_activity_title"
         android:name="org.chromium.chrome.browser.webauth.authenticator.CableAuthenticatorActivity"
+        android:permission="com.google.android.gms.auth.cryptauth.permission.CABLEV2_SERVER_LINK"
         android:theme="@style/Theme.Chromium.Activity.Fullscreen">
       <intent-filter>  # DIFF-ANCHOR: 5873407a
         <action android:name="android.hardware.usb.action.USB_ACCESSORY_ATTACHED"/>

chrome/android/java/AndroidManifest.xml

@@ -853,12 +853,11 @@ by a child template that "extends" this file.
         <activity android:name="org.chromium.chrome.browser.webauth.authenticator.CableAuthenticatorActivity"
             android:theme="@style/Theme.Chromium.Activity.Fullscreen"
             android:label="@string/cablev2_activity_title"
-            android:exported="false">
-            <!-- This has an intent filter but is not exported. This works
-            because the intent is sent by the Android system, not another
-            application. We want to limit this activity to only be invoked by
-            Chromium or the OS because otherwise applications could fool
-            Chromium into communicating with a fake USB device. -->
+            android:permission="com.google.android.gms.auth.cryptauth.permission.CABLEV2_SERVER_LINK"
+            android:exported="true">
+            <!-- This activity can be started by GMSCore, and is thus exported
+            with a permission set, or can be started by the Android system in
+            the case that a USB device is attached. -->
             <intent-filter>
                  <action android:name="android.hardware.usb.action.USB_ACCESSORY_ATTACHED" />
             </intent-filter>