AW: Separate build target for webview dev ui launcher icon

Add a target for merging the manifest file where a launcher icon is
added for WebView dev UI. This removes manifest merging from
"dev_ui_resources" definition and consequently from
"//android_webview:apk:apk_java". This makes it safe to depend on
"apk_java" target without triggering any manifest merging for targets
like WebView instrumentation tests.

Fixed: 1020444
Test: `webview_devui_show_icon=true` and bin/run_webview_instrumentation_test_apk
Test: Manually verify launcher icon after building SystemWebView, MonoChrome and Trichrome
Change-Id: Iba7e714ddb0b525828445565696e94327c9dfd84
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1904674
Commit-Queue: Richard Coles <torne@chromium.org>
Reviewed-by: Richard Coles <torne@chromium.org>
Reviewed-by: Andrew Grieve <agrieve@chromium.org>
Reviewed-by: Nate Fischer <ntfschr@chromium.org>
Auto-Submit: Hazem Ashmawy <hazems@chromium.org>
Cr-Commit-Position: refs/heads/master@{#714673}

android_webview/apk/BUILD.gn

@@ -108,10 +108,12 @@ android_resources("icon_resources") {
 android_resources("devui_resources") {
   resource_dirs = [ "java/res_devui" ]
   custom_package = "org.chromium.android_webview.devui"
+}
 
-  if (webview_devui_show_icon) {
+android_resources("devui_launcher_icon_resources") {
+  resource_dirs = []
+  custom_package = "org.chromium.android_webview.devui.icon"
   android_manifest = "java/DeveloperUiLauncherManifest.xml"
-  }
 }
 
 jinja_template("system_webview_manifest") {

android_webview/system_webview_apk_tmpl.gni

@@ -43,6 +43,10 @@ template("system_webview_apk_tmpl") {
       alternative_android_sdk_dep = webview_framework_dep
     }
 
+    if (webview_devui_show_icon) {
+      deps += [ "//android_webview/apk:devui_launcher_icon_resources" ]
+    }
+
     _use_trichrome_library =
         defined(use_trichrome_library) && use_trichrome_library
 

chrome/android/chrome_public_apk_tmpl.gni

@@ -373,6 +373,10 @@ template("monochrome_public_common_apk_or_module_tmpl") {
       ]
       loadable_modules += [ "$root_out_dir/libcrashpad_handler_trampoline.so" ]
 
+      if (webview_devui_show_icon) {
+        _deps += [ "//android_webview/apk:devui_launcher_icon_resources" ]
+      }
+
       if (android_64bit_target_cpu && build_apk_secondary_abi &&
           (!defined(invoker.is_64_bit_browser) || !invoker.is_64_bit_browser ||
            invoker.include_32_bit_webview)) {