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 kAlphaEnabledMissingPermission[] =
+    "The alphaEnabled option requires app.window.alpha permission.";
+#if !defined(USE_AURA)

[jackhou1, 2014/07/22 05:35:35]

It might be better to just allow apps to set this regardless of platform, but
add documentation indicating that they need to check AppWindow.alphaEnabled().

[garykac, 2014/07/25 22:50:31]

Done.  Actually, that matches the current doc for this feature.

The downside is that we don't have a way to return a "why" error message
(missing permission vs. platform not supported), but the fallback of creating a
non-opaque window is clearly preferable.

[jackhou1, 2014/07/29 23:39:10]

Oops, I should have been clearer. We should probably still keep the missing
permission error. My reasoning is that a developer would just want to know how
to make the errors go away. So we can tell them to add the permission, but
there's not much they can do about a platform not supporting alpha.

[garykac, 2014/08/04 23:11:53]

Done.

+const char kAlphaEnabledNotSupported[] =
+    "Alpha-blended windows are not supported on this platform.";
+#endif
+const char kAlphaEnabledWrongChannel[] =
+    "The alphaEnabled option requires beta channel or newer.";
 }  // 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 158 matching lines @@
     if (GetCurrentChannel() <= chrome::VersionInfo::CHANNEL_DEV ||
         GetExtension()->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() &&
-        (GetExtension()->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 (!GetExtension()->permissions_data()->HasAPIPermission(
+              APIPermission::kAlphaEnabled)) {
+        error_ = app_window_constants::kAlphaEnabledMissingPermission;
+        return false;
+      }
+#if !defined(USE_AURA)
+      error_ = app_window_constants::kAlphaEnabledNotSupported;
+      return false;
+#else
+      create_params.alpha_enabled = *options->alpha_enabled;
+#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