Remove most android_webview_build conditions from build.

build/config/gcc/gcc_version.gni

 # 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.
 
 if (is_android) {
-  import("//build/config/android/config.gni")
-  if (is_android_webview_build) {
-    gcc_version = 48
-  } else {
-    gcc_version = 49
-  }
+  gcc_version = 49
 } else if (current_toolchain == "//build/toolchain/cros:target" ||
            current_toolchain == "//build/toolchain/linux:mipsel") {
   gcc_version = exec_script("../../compiler_version.py",
                             [
                               "target",
                               "compiler",
                             ],
                             "value")
 } else if (current_toolchain == "//build/toolchain/linux:x64" ||
            current_toolchain == "//build/toolchain/linux:x86") {
   # These are both the same and just use the default gcc on the system.
   gcc_version = exec_script("../../compiler_version.py",
                             [
                               "host",
                               "compiler",
                             ],
                             "value")
 } else {
   gcc_version = 0
 }