Add support for transparent background API

chrome/browser/extensions/api/app_window/app_window_api.cc

Index: chrome/browser/extensions/api/app_window/app_window_api.cc
diff --git a/chrome/browser/extensions/api/app_window/app_window_api.cc b/chrome/browser/extensions/api/app_window/app_window_api.cc
index 4f2b68eaf5672670e0a9279fb614087e130a07c2..cc848389ae3249c5c3ac525391cdd87742556994 100644
--- a/chrome/browser/extensions/api/app_window/app_window_api.cc
+++ b/chrome/browser/extensions/api/app_window/app_window_api.cc
@@ -41,6 +41,8 @@ namespace extensions {
 namespace app_window_constants {
 const char kInvalidWindowId[] =
     "The window id can not be more than 256 characters long.";
+const char kMissingPermissionAlphaEnabled[] =
+    "The alphaEnabled option requires app.window.alpha permission.";
 const char kInvalidColorSpecification[] =
     "The color specification could not be parsed.";
 const char kInvalidChannelForFrameOptions[] =
@@ -223,12 +225,30 @@ bool AppWindowCreateFunction::RunAsync() {
     if (!GetFrameOptions(*options, &create_params))
       return false;
 
-    if (options->transparent_background.get() &&
-        (GetExtension()->HasAPIPermission(APIPermission::kExperimental) ||
-         CommandLine::ForCurrentProcess()->HasSwitch(
-             switches::kEnableExperimentalExtensionApis))) {
-      create_params.transparent_background = *options->transparent_background;
+#if defined(USE_AURA)
+    if (options->alpha_enabled.get()) {
+      bool allow_alpha_enabled = false;
+      // For now, continue to support this if Experimental is set (any channel).
+      // TODO(garykac) Remove this once the permission moves to stable.
+      if (GetExtension()->HasAPIPermission(APIPermission::kExperimental) ||
+          CommandLine::ForCurrentProcess()->HasSwitch(
+              switches::kEnableExperimentalExtensionApis)) {
+        allow_alpha_enabled = true;
+      }
+      // Support alphaEnabled permission on dev channel.
+      if (GetCurrentChannel() <= chrome::VersionInfo::CHANNEL_DEV) {
+        if (GetExtension()->HasAPIPermission(APIPermission::kAlphaEnabled)) {
+          allow_alpha_enabled = true;
+        } else {
+          error_ = app_window_constants::kMissingPermissionAlphaEnabled;
+          return false;
+        }
+      }
+      if (allow_alpha_enabled) {
+        create_params.alpha_enabled = *options->alpha_enabled;
+      }
     }
+#endif
 
     if (options->hidden.get())
       create_params.hidden = *options->hidden.get();