Use thumb versions of external libraries with ARMv7.

build/common.gypi

 # Copyright (c) 2012 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.
 
 # IMPORTANT:
 # Please don't directly include this file if you are building via gyp_chromium,
 # since gyp_chromium is automatically forcing its inclusion.
 {
   # Variables expected to be overriden on the GYP command line (-D) or by
   # ~/.gyp/include.gypi.
@@ skipping 146 matching lines @@
         # build system.
         'android_webview_build%': 0,
 
         # This is set when building the Android WebView in ninja for the
         # telemetry bot.
         'android_webview_telemetry_build%': 0,
 
         # Set ARM architecture version.
         'arm_version%': 7,
 
+        # Use Thumb on ARMv7
+        'arm_thumb%':0,
+
         # Use aurax11 for clipboard implementation. This is true on linux_aura.
         'use_clipboard_aurax11%': 0,
 
         # goma settings.
         # 1 to use goma.
         # If no gomadir is set, it uses the default gomadir.
         'use_goma%': 0,
         'gomadir%': '',
 
         # The system root for cross-compiles. Default: none.
@@ skipping 115 matching lines @@
       'android_channel%': '<(android_channel)',
       'android_webview_build%': '<(android_webview_build)',
       'android_webview_telemetry_build%': '<(android_webview_telemetry_build)',
       'use_goma%': '<(use_goma)',
       'gomadir%': '<(gomadir)',
       'enable_app_list%': '<(enable_app_list)',
       'use_default_render_theme%': '<(use_default_render_theme)',
       'buildtype%': '<(buildtype)',
       'branding%': '<(branding)',
       'arm_version%': '<(arm_version)',
+      'arm_thumb%': '<(arm_thumb)',
       'sysroot%': '<(sysroot)',
       'chroot_cmd%': '<(chroot_cmd)',
       'system_libdir%': '<(system_libdir)',
 
       # Set to 1 to enable fast builds. Set to 2 for even faster builds
       # (it disables debug info for fastest compilation - only for use
       # on compile-only bots).
       'fastbuild%': 0,
 
       # Set to 1 to not store any build metadata, e.g. ifdef out all __DATE__
@@ skipping 1500 matching lines @@
       }],
       ['chromecast==1', {
         'enable_mpeg2ts_stream_parser%': 1,
         'ffmpeg_branding%': 'Chrome',
         'ozone_platform_ozonex%': 1,
         'use_playready%': 0,
         'conditions': [
           ['target_arch=="arm"', {
             'arm_arch%': '',
             'arm_tune%': 'cortex-a9',
             'arm_thumb%': 1,

[Nico, 2014/11/03 18:03:53]

Does this still work?

             'video_hole%': 1,
           }],
         ],
       }],
       ['android_webview_build==1', {
         # When building the WebView in the Android tree, jarjar will remap all
         # the class names, so the JNI generator needs to know this.
         'jni_generator_jarjar_file': '../android_webview/build/jarjar-rules.txt',
       }],
       ['OS=="linux" and target_arch!="mipsel"', {
@@ skipping 421 matching lines @@
       ['branding=="Chrome" and (OS=="win" or OS=="mac" or OS=="ios" or chromeos==1)', {
         'enable_rlz%': 1,
       }],
 
       # Set default compiler flags depending on ARM version.
       ['arm_version==6 and android_webview_build==0', {
         'arm_arch%': 'armv6',
         'arm_tune%': '',
         'arm_fpu%': 'vfp',
         'arm_float_abi%': 'softfp',
         'arm_thumb%': 0,

[Nico, 2014/11/03 18:03:54]

Isn't all the arm_thumb stuff here now one scope to far out?

[Fabrice (no longer in Chrome), 2014/11/03 18:31:22]

Blasted! You are right, gyp is confusing :/
The alternative is to nest everything further than it already is.
Adding the new variable near the libraries to avoid duplication.

       }],
       ['arm_version==7 and android_webview_build==0', {
         'arm_arch%': 'armv7-a',
         'arm_tune%': 'generic-armv7-a',
         'conditions': [
           ['arm_neon==1', {
             'arm_fpu%': 'neon',
           }, {
             'arm_fpu%': 'vfpv3-d16',
           }],
@@ skipping 60 matching lines @@
       # Do not disable seccomp_bpf anywhere without talking to
       # security@chromium.org!
       ['((OS=="linux" or OS=="android") and '
            '(target_arch=="ia32" or target_arch=="x64" or '
              'target_arch=="arm" or target_arch=="mipsel" or '
              'target_arch=="arm64"))', {
          'use_seccomp_bpf%': 1,
       }, {
          'use_seccomp_bpf%': 0,
       }],
+
+      ['arm_thumb==1', {
+        'thumb_option%': "-mthumb",
+      }, {
+        'thumb_option%': "",
+      }],
+
       # Set component build with LTO until all tests pass.
       # This also reduces link time.
       ['use_lto==1', {
         'component%': "shared_library",
       }],
     ],
 
     # older history files use fts2 instead of fts3
     'sqlite_enable_fts2%': '<(support_pre_M6_history_database)',
 
@@ skipping 1437 matching lines @@
                 ],
                 'ldflags': [
                   '-m64',
                 ],
               }],
             ],
           }],
           ['target_arch=="arm"', {
             'target_conditions': [
               ['_toolset=="target"', {
+                'cflags': [ '<(thumb_option)' ],
                 'conditions': [
                   ['clang==0', {
                     'cflags_cc': [
                       # The codesourcery arm-2009q3 toolchain warns at that the ABI
                       # has changed whenever it encounters a varargs function. This
                       # silences those warnings, as they are not helpful and
                       # clutter legitimate warnings.
                       '-Wno-abi',
                     ],
                   }],
@@ skipping 53 matching lines @@
                       '-mfloat-abi=<(arm_float_abi)',
                     ],
                     'conditions': [
                       ['use_lto==1 or use_lto_o2==1', {
                         'ldflags': [
                           '-mfloat-abi=<(arm_float_abi)',
                         ],
                       }],
                     ],
                   }],
-                  ['arm_thumb==1', {
-                    'cflags': [
-                      '-mthumb',
-                    ],
-                    'conditions': [
-                      ['use_lto==1 or use_lto_o2==1', {
-                        'ldflags': [
-                          '-mthumb',
-                        ],
-                      }],
+                  ['use_lto==1 or use_lto_o2==1', {
+                    'ldflags': [
+                      '<(thumb_option)',
                     ],
                   }],
                   ['OS=="android"', {
                     # Most of the following flags are derived from what Android
                     # uses by default when building for arm, reference for which
                     # can be found in the following file in the Android NDK:
                     # toolchains/arm-linux-androideabi-4.9/setup.mk
                     'cflags': [
                       # The tree-sra optimization (scalar replacement for
                       # aggregates enabling subsequent optimizations) leads to
@@ skipping 733 matching lines @@
                 'cflags': [
                   '--sysroot=<(android_ndk_sysroot)',
                 ],
                 'ldflags': [
                   '--sysroot=<(android_ndk_sysroot)',
                   '-nostdlib',
                 ],
                 'libraries': [
                   '-l<(android_stlport_library)',
                   # Manually link the libgcc.a that the cross compiler uses.
-                  '<!(<(android_toolchain)/*-gcc -print-libgcc-file-name)',
+                  '<!(<(android_toolchain)/*-gcc <(thumb_option) -print-libgcc-file-name)',
                   '-lc',
                   '-ldl',
                   '-lm',
                 ],
               }],
               ['android_webview_build==1', {
                 'cflags': [
                   # Android predefines this as 1; undefine it here so Chromium
                   # can redefine it later to be 2 for chromium code and unset
                   # for third party code. This works because cflags are added
@@ skipping 44 matching lines @@
               # NOTE: The stlport header include paths below are specified in
               # cflags rather than include_dirs because they need to come
               # after include_dirs. Think of them like system headers, but
               # don't use '-isystem' because the arm-linux-androideabi-4.4.3
               # toolchain (circa Gingerbread) will exhibit strange errors.
               # The include ordering here is important; change with caution.
               ['android_webview_build==0', {
                 'cflags': [
                   '-isystem<(android_stlport_include)',
                 ],
-                'ldflags': [
-                  '-L<(android_stlport_libs_dir)',
+                'conditions': [
+                  ['target_arch=="arm" and arm_thumb==1', {
+                    'ldflags': [ '-L<(android_stlport_libs_dir)/thumb' ]
+                  }, {
+                    'ldflags': [ '-L<(android_stlport_libs_dir)' ]
+                  }],
                 ],
               }, { # else: android_webview_build!=0
                 'aosp_build_settings': {
                   # Specify that we want to statically link stlport from the
                   # NDK. This will provide all the include and library paths
                   # automatically at build time, and link the right library.
                   'LOCAL_NDK_STL_VARIANT': 'stlport_static',
                 },
               }],
               ['target_arch=="ia32"', {
@@ skipping 1166 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',
   },
 }