Add semantics to apply gpu blakclist to AMD swichable when a discrete/integrated GPU is in use

gpu/config/gpu_control_list_format.txt

 // Copyright (c) 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.
 
 // A valid gpu control list json file is in the format of
 // {
 //   "version": "x.y",
 //   "entries": [
 //     { // entry 1
 //     },
 //     ...
 //     { // entry n
 //     }
 //   ]
 // }
 //
 // Each entry contains the following fields (fields are optional unless
 // specifically described as mandatory below):
 // 1. "id" is an integer.  0 is reserved.  This field is mandatory.
 // 2. "os" contains "type" and an optional "version". "type" could be "macosx",
 //    "linux", "win", "chromeos", or "any".  "any" is the same as not specifying
 //    "os".
 //    "version" is a VERSION structure (defined below).
 // 3. "vendor_id" is a string.  0 is reserved.
 // 4. "device_id" is an array of strings.  0 is reserved.
-// 5. "multi_gpu_style" is a string, valid values include "optimus", and
-//    "amd_switchable".
+// 5. "multi_gpu_style" is a string, valid values include:
+//      a) "optimus": NVIDIA dual GPU
+//      b) "amd_switchable": AMD dual GPU
+//      c) "amd_switchable_integrated": AMD dual GPU, integrated GPU is active
+//      d) "amd_switchable_discrete": AMD dual GPU, discrete GPU is active
+//    c) and d) are only valid on Win, as on Mac we can switch GPU on the fly.
 // 6. "multi_gpu_category" is a string, valid values include "any", "primary",
 //    "secondary", and "active". If unspecified, the default value is "primary".
 //    See gpu_control_list.h for more details on the meanings of the strings.
 // 7. "driver_vendor" is a STRING structure (defined below).
 // 8. "driver_version" is a VERSION structure (defined below).
 // 9. "driver_date" is a VERSION structure (defined below).
 //    The version is interpreted as "year.month.day".
 // 10. "gl_type" is a string, valid values include "gl", "gles", and "angle".
 //    If "gl_version" is specified and "gl_type" is not, use the default value.
 //    The default value on Android is "gles", on Windows is "angle", on other
@@ skipping 34 matching lines @@
 //
 // STRING includes "op" and "value".  "op" can be any of the following values:
 // "contains", "beginwith", "endwith", "=".  "value" is a string.
 //
 // FLOAT includes "op" "value", and "value2".  "op" can be any of the
 // following values: "=", "<", "<=", ">", ">=", "any", "between".  "value2" is
 // only used if "op" is "between".  "value" is used for all "op" values except
 // "any". "value" and "value2" are valid float numbers.
 // INT is very much like FLOAT, except that the values need to be integers.