Add a gyp "buildtype" variable to differentiate official release builds.

build/common.gypi

 # Copyright (c) 2009 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.
 
 {
   'variables': {
     # .gyp files should set chromium_code to 1 if they build Chromium-specific
     # code, as opposed to external code.  This variable is used to control
     # such things as the set of warnings to enable, and whether warnings are
     # treated as errors.
     'chromium_code%': 0,
 
     # Variables expected to be overriden on the GYP command line (-D) or by
     # ~/.gyp/include.gypi.
 
     # Override chromium_mac_pch and set it to 0 to suppress the use of
     # precompiled headers on the Mac.  Prefix header injection may still be
     # used, but prefix headers will not be precompiled.  This is useful when
     # using distcc to distribute a build to compile slaves that don't
     # share the same compiler executable as the system driving the compilation,
     # because precompiled headers rely on pointers into a specific compiler
     # executable's image.  Setting this to 0 is needed to use an experimental
     # Linux-Mac cross compiler distcc farm.
     'chromium_mac_pch%': 1,
 
     # Override branding to select the desired branding flavor.
     'branding%': 'Chromium',
 
+    # Override buildtype to select the desired build flavor.
+    # Dev - everyday build for development/testing
+    # Official - release build (generally implies additional processing)
+    # TODO(mmoss) Once 'buildtype' is fully supported (e.g. Windows gyp
+    # conversion is done), some of the things which are now controlled by
+    # 'branding', such as symbol generation, will need to be refactored based
+    # on 'buildtype' (i.e. we don't care about saving symbols for non-Official
+    # builds).
+    'buildtype%': 'Dev',
+
     # Set to 1 to enable code coverage.  In addition to build changes
     # (e.g. extra CFLAGS), also creates a new target in the src/chrome
     # project file called "coverage".
     # Currently ignored on Windows.
     'coverage%': 0,
 
     # Overridable specification for potential use of alternative
     # JavaScript engines.
     'javascript_engine%': 'v8',
 
@@ skipping 500 matching lines @@
     # settings in target dicts.  SYMROOT is a special case, because many other
     # Xcode variables depend on it, including variables such as
     # PROJECT_DERIVED_FILE_DIR.  When a source group corresponding to something
     # like PROJECT_DERIVED_FILE_DIR is added to a project, in order for the
     # files to appear (when present) in the UI as actual files and not red
     # red "missing file" proxies, the correct path to PROJECT_DERIVED_FILE_DIR,
     # and therefore SYMROOT, needs to be set at the project level.
     'SYMROOT': '<(DEPTH)/xcodebuild',
   },
 }