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..9d57308fb7fe4de8cbc164cdbea2c6891e003a36 100644
--- a/chrome/browser/extensions/api/app_window/app_window_api.cc
+++ b/chrome/browser/extensions/api/app_window/app_window_api.cc
@@ -50,6 +50,11 @@ const char kInactiveColorWithoutColor[] =
     "frame.inactiveColor must be used with frame.color.";
 const char kConflictingBoundsOptions[] =
     "The $1 property cannot be specified for both inner and outer bounds.";
+
+#if defined(USE_AURA)
+const char kMissingPermissionAlphaEnabled[] =
+    "The alphaEnabled option requires app.window.alpha permission.";
+#endif
 }  // namespace app_window_constants
 
 const char kNoneFrameOption[] = "none";
@@ -223,12 +228,30 @@ 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)

[benwells, 2014/05/12 04:25:17]

Why is this gated on aura? If you try to use this on another platform and don't
have the permission, you should get the same error.

[garykac, 2014/07/09 23:19:21]

Done.

+    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) ||

[benwells, 2014/05/12 04:25:17]

After thinking about it I'd prefer to remove access via experimental flag since
we're restricting to dev channel. Are there real apps you know you'll break?

[garykac, 2014/07/09 23:19:21]

I don't know of any apps. Removed.

+          CommandLine::ForCurrentProcess()->HasSwitch(
+              switches::kEnableExperimentalExtensionApis)) {
+        allow_alpha_enabled = true;
+      }
+      // Support alphaEnabled permission on dev channel.
+      if (GetCurrentChannel() <= chrome::VersionInfo::CHANNEL_DEV) {

[benwells, 2014/05/12 04:25:17]

There should also be an error if the user tries to access this and they are on
stable / beta.

[garykac, 2014/07/09 23:19:21]

Done. Handled in the _permission_features.json.

+        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();