Add app.window.alphaEnabled() and onAlphaEnabledChanged.

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 kTransparentBackgroundNeedsFrameNone[] =
+    "\"transparent_background\" can only be used with \"frame: none\".";
 }  // 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->transparent_background.get()) {
+      if (create_params.frame != AppWindow::FRAME_NONE) {
+        error_ = app_window_constants::kTransparentBackgroundNeedsFrameNone;
+        return false;
+      }
+      if (GetExtension()->permissions_data()->HasAPIPermission(
+              APIPermission::kExperimental) ||
+          CommandLine::ForCurrentProcess()->HasSwitch(
+              switches::kEnableExperimentalExtensionApis)) {
+        create_params.transparent_background = *options->transparent_background;
+      }

[levin, 2014/07/15 20:40:05]

Changes in this file seem unrelated to the rest of the goals.

This change seems more about making the api more bulletproof which I applaud,
but it could this be in a separate cl (since isn't part of the core changes that
are necessary to make things work). 

imo, the smaller the cl the less risky (and the more possible to get merge
approval).

[jackhou1, 2014/07/16 01:26:29]

Seems fair, the feature is still behind a flag after all. I'll put these in
another CL.

     }
 
     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