Add support for transparent background API

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

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/browser/extensions/api/app_window/app_window_api.h"
 
 #include "apps/app_window.h"
 #include "apps/app_window_contents.h"
 #include "apps/app_window_registry.h"
 #include "apps/apps_client.h"
@@ skipping 36 matching lines @@
     "The color specification could not be parsed.";
 const char kColorWithFrameNone[] = "Windows with no frame cannot have a color.";
 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.";
 const char kAlwaysOnTopPermission[] =
     "The \"app.window.alwaysOnTop\" permission is required.";
 const char kInvalidUrlParameter[] =
     "The URL used for window creation must be local for security reasons.";
+const char kAlphaEnabledWrongChannel[] =
+    "The alphaEnabled option requires beta channel or newer.";

[benwells, 2014/08/05 23:37:05]

Normally we restrict to dev, not beta. Any reason to let beta use this?

[garykac, 2014/08/07 03:54:00]

I was matching the Shape permissions, but that's not really necessary. Changed
to dev.

+const char kAlphaEnabledMissingPermission[] =
+    "The alphaEnabled option requires app.window.alpha permission.";
 }  // namespace app_window_constants
 
 const char kNoneFrameOption[] = "none";
   // TODO(benwells): Remove HTML titlebar injection.
 const char kHtmlFrameOption[] = "experimental-html";
 
 namespace {
 
 // Opens an inspector window and delays the response to the
 // AppWindowCreateFunction until the DevToolsWindow has finished loading, and is
@@ skipping 160 matching lines @@
     if (GetCurrentChannel() <= chrome::VersionInfo::CHANNEL_DEV ||
         extension()->location() == extensions::Manifest::COMPONENT) {
       if (options->type == extensions::api::app_window::WINDOW_TYPE_PANEL) {
         create_params.window_type = AppWindow::WINDOW_TYPE_PANEL;
       }
     }
 
     if (!GetFrameOptions(*options, &create_params))
       return false;
 
-    if (options->transparent_background.get() &&
-        (extension()->permissions_data()->HasAPIPermission(
-             APIPermission::kExperimental) ||
-         CommandLine::ForCurrentProcess()->HasSwitch(
-             switches::kEnableExperimentalExtensionApis))) {
-      create_params.transparent_background = *options->transparent_background;
+    if (options->alpha_enabled.get()) {
+      if (GetCurrentChannel() > chrome::VersionInfo::CHANNEL_BETA) {
+        error_ = app_window_constants::kAlphaEnabledWrongChannel;
+        return false;
+      }
+      if (!extension()->permissions_data()->HasAPIPermission(
+              APIPermission::kAlphaEnabled)) {
+        error_ = app_window_constants::kAlphaEnabledMissingPermission;
+        return false;
+      }
+#if defined(USE_AURA)
+      create_params.alpha_enabled = *options->alpha_enabled;
+#else
+      // Transparency is only supported on Aura.
+      // Fallback to creating an opaque window (by ignoring alphaEnabled).
+#endif
     }
 
     if (options->hidden.get())
       create_params.hidden = *options->hidden.get();
 
     if (options->resizable.get())
       create_params.resizable = *options->resizable.get();
 
     if (options->always_on_top.get()) {
       create_params.always_on_top = *options->always_on_top.get();
@@ skipping 239 matching lines @@
 
   if (options.frame->as_frame_options->inactive_color.get()) {
     error_ = app_window_constants::kInactiveColorWithoutColor;
     return false;
   }
 
   return true;
 }
 
 }  // namespace extensions