Add ErrorConsole UI for Extension Install Warnings

chrome/browser/resources/extensions/extension_error.css

Index: chrome/browser/resources/extensions/extension_error.css
diff --git a/chrome/browser/resources/extensions/extension_error.css b/chrome/browser/resources/extensions/extension_error.css
new file mode 100644
index 0000000000000000000000000000000000000000..14ca70b6f83ad4c9e5378a28d3c690295059e94b
--- /dev/null
+++ b/chrome/browser/resources/extensions/extension_error.css
@@ -0,0 +1,50 @@
+/* Copyright 2013 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. */
+
+.extension-error-list a {
+  cursor: pointer;
+}
+
+.extension-error-list-contents {
+  -webkit-padding-start: 20px;
+  list-style-type: none;
+}
+
+.extension-error-list-show-more {
+  text-align: center;
+  width: 100%;
+}
+
+.extension-error-simple-wrapper {
+  width: 100%;
+}
+
+.extension-error-icon {
+  -webkit-margin-end: 3px;
+  -webkit-margin-start: 3px;
+  height: 15px;
+  vertical-align: middle;
+  width: 15px;
+}
+
+.extension-error-log .extension-error-message {
+  color: #333;
+}
+.extension-error-log .extension-error-icon {
+  content: url('extension_error_log.png');
+}
+
+.extension-error-warn .extension-error-message {

[Dan Beam, 2013/08/29 00:24:30]

hmmm, error-warn and error-error are awkward.  extension-notification-errors
extension-notification-warnings (though maybe there are other things that mean
"notification")?

[Devlin, 2013/08/29 21:02:04]

Yeah, I thought error-error was odd, too.  But I think it's best to keep
everything with the "ExtensionError" name, since that's what we're using
everywhere else (C++ side and JS).  How about extension-error-severity-info,
...severity-warning, and ...severity-fatal?  Keeps extension-error prefix while
still providing context and not sounding (quite) as weird?

+  color: rgba(250, 145, 0, 255);
+}
+.extension-error-warn .extension-error-icon {
+  content: url('extension_error_warn.png');
+}
+
+.extension-error-error .extension-error-message {
+  color: rgba(200, 50, 50, 255);
+}
+.extension-error-error .extension-error-icon {
+  content: url('extension_error_error.png');
+}