Basic underpinnings of the gyp equivalent of the Linux SHARED=1 build:...

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.
@@ skipping 13 matching lines @@
     'chromium_mac_pch%': 1,
 
     # Override branding to select the desired branding flavor.
     'branding%': 'Chromium',
 
     # 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,
+
+    # To do a shared build on linux we need to be able to choose between type
+    # static_library and shared_library. We default to doing a static build
+    # but you can override this with "gyp -Dlibrary=shared_library" or you
+    # can add the following line (without the #) to ~/.gyp/include.gypi
+    # {'variables': {'library': 'shared_library'}}
+    # to compile as shared by default
+    'library%': 'static_library',
   },
   'target_defaults': {
     'conditions': [
       ['branding=="Chrome"', {
         'defines': ['GOOGLE_CHROME_BUILD'],
       }, {  # else: branding!="Chrome"
         'defines': ['CHROMIUM_BUILD'],
       }],
       ['coverage!=0', {
         'conditions': [
@@ skipping 338 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',
   },
 }