Update to Chromium revision 9cedf753 (#418732)

- Simplify usage of OnBeforePluginLoad (issue #2015)
- Switch crash reporting from crashpad to breakpad on Windows and OS X.
  Adds a new chrome_elf.dll dependency on Windows (issue #1995)
- Remove CefTextfield::GetPlaceholderTextColor() method which is no
  longer supported by Chromium.

libcef/common/extensions/api/BUILD.gn

@@ -4,10 +4,20 @@
 
 import("//build/json_schema_api.gni")
 import("//tools/json_schema_compiler/json_features.gni")
-import("schemas.gni")
 
 # TODO(cef): Enable if/when CEF exposes its own Mojo APIs. See README.txt for
 # details.
+#schema_sources = [
+#  # TODO(cef): Add CEF-specific Mojo APIs here.
+#]
+#
+#uncompiled_sources = [
+#]
+#
+#root_namespace = "extensions::api::cef::%(namespace)s"
+#schema_include_rules = "//cef/libcef/browser/extensions/api:extensions::api::cef::%(namespace)s"
+#schema_dependencies = [ "//extensions/common/api" ]
+#
 #json_schema_api("api") {
 #  sources = schema_sources
 #  schemas = true

libcef/common/extensions/api/README.txt

@@ -9,7 +9,7 @@ To add a new extension API implemented only in CEF ***:
 1. Add libcef/common/extensions/api/<api>.idl or .json file which defines the
    API.
 2. Add <api>.idl or .json to the 'schema_sources' list in
-   libcef/common/extensions/api/schemas.gni. Serialization code will be
+   libcef/common/extensions/api/BUILD.gn. Serialization code will be
    generated based on this list in step 5.
 3. Add an entry in the libcef/common/extensions/api/_*_features.json files if
    necessary [1].

libcef/common/extensions/api/schemas.gni

@@ -1,14 +0,0 @@
-# Copyright 2016 The Chromium Embedded Framework Authors. Portions copyright
-# 2014 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.
-
-schema_sources = [
-  # TODO(cef): Add CEF-specific Mojo APIs here.
-]
-
-uncompiled_sources = [
-]
-
-root_namespace = "extensions::api::cef::%(namespace)s"
-schema_include_rules = "//cef/libcef/browser/extensions/api:extensions::api::cef::%(namespace)s"
-schema_dependencies = [ "//extensions/common/api" ]