Clean up AndroidManifest variable.

sandboxed_service_extra_flags is only used to set
visibleToInstantApps=true, which should always be true for both WebView
and Monochrome. Just set the attribute in the manifest directly and
remove the variable entirely to simplify the configuration and remove
the possibility that someone makes a new target which forgets to set it
(since the breakage caused by not setting this is subtle and easy to
miss).

Bug: 797014
Change-Id: Iec2075c23c4e71302a10d1f15b83b290618f1a32
Reviewed-on: https://chromium-review.googlesource.com/920262Reviewed-by: Tobias Sargeant <tobiasjs@chromium.org>
Reviewed-by: Ted Choc <tedchoc@chromium.org>
Commit-Queue: Richard Coles <torne@chromium.org>
Cr-Commit-Position: refs/heads/master@{#539225}

android_webview/BUILD.gn

@@ -102,10 +102,7 @@ java_cpp_enum("aw_safe_browsing_action") {
 jinja_template("system_webview_manifest") {
   input = "apk/java/AndroidManifest.xml"
   output = system_webview_android_manifest
-  variables = [
-    "package=$system_webview_package_name",
-    "sandboxed_service_extra_flags=android:visibleToInstantApps=\"true\"",
-  ]
+  variables = [ "package=$system_webview_package_name" ]
 }
 
 webview_repack_locales("repack_locales") {

android_webview/apk/java/AndroidManifest.xml

@@ -71,7 +71,7 @@
                      android:exported="true"
                      android:externalService="true"
                      tools:ignore="ExportedService"
-                     {{sandboxed_service_extra_flags|default('')}} />
+                     android:visibleToInstantApps="true" />
         {% endfor %}
         <meta-data android:name="org.chromium.content.browser.NUM_PRIVILEGED_SERVICES"
                    android:value="0"/>

chrome/android/java/AndroidManifest.xml

@@ -1051,8 +1051,8 @@ by a child template that "extends" this file.
             {% if (sandboxed_service_exported|default(false)) == 'true' %}
             android:externalService="true"
             tools:ignore="ExportedService"
-            {% endif %}
-            {{sandboxed_service_extra_flags|default('')}} />
+            android:visibleToInstantApps="true"
+            {% endif %} />
         {% endfor %}
 
         {% set num_privileged_services = 3 %}

chrome/android/monochrome_android_manifest_jinja_variables.gni

@@ -6,5 +6,4 @@ monochrome_android_manifest_jinja_variables = [
   "min_sdk_version=24",
   "sandboxed_service_exported=true",
   "use32bitAbi=android:use32bitAbi=\"true\"",
-  "sandboxed_service_extra_flags=android:visibleToInstantApps=\"true\"",
 ]