Linux/CrOS smooth scrolling support - behind a flag.

build/features_override.gypi

 # Copyright (c) 2011 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.
 
 # This file is only included in full-chromium builds, and overrides the
 # feature_defines variable in
 # third_party/WebKit/Source/WebKit/chromium/features.gypi.
 {
   'variables': {
     # WARNING: This list of strings completely replaces the list in
@@ skipping 65 matching lines @@
       # We can't define it here because it should be present only
       # in Debug or release_valgrind_build=1 builds.
       'WTF_USE_WEBP=1',
       'WTF_USE_WEBKIT_IMAGE_DECODERS=1',
     ],
     # We have to nest variables inside variables so that they can be overridden
     # through GYP_DEFINES.
     'variables': {
       'use_accelerated_compositing%': 1,
       'use_threaded_compositing%': 0,
+      'enable_smooth_scrolling%': 0,
       'enable_svg%': 1,
       'enable_touch_events%': 1,
       'use_skia_gpu%': 0,
     },
     'use_accelerated_compositing%': '<(use_accelerated_compositing)',
     'use_threaded_compositing%': '<(use_threaded_compositing)',
+    'enable_smooth_scrolling%': '<(enable_smooth_scrolling)',
     'enable_svg%': '<(enable_svg)',
     'enable_touch_events%': '<(enable_touch_events)',
     'conditions': [
       ['use_accelerated_compositing==1', {
         'feature_defines': [
           'WTF_USE_ACCELERATED_COMPOSITING=1',
           'ENABLE_3D_RENDERING=1',
           'ENABLE_ACCELERATED_2D_CANVAS=1',
         ],
         'use_accelerated_compositing': 1,
@@ skipping 16 matching lines @@
       ['OS!="mac"', {
         'feature_defines': [
           'WTF_USE_WEBAUDIO_FFMPEG=1',
         ],
       }],
       ['enable_register_protocol_handler==1', {
         'feature_defines': [
           'ENABLE_REGISTER_PROTOCOL_HANDLER=1',
         ],
       }],
+      ['OS=="linux" and enable_smooth_scrolling==1', {

[darin (slow to review), 2011/05/31 20:40:24]

i don't quite understand why this is OS==linux.  why don't we just make the
runtime flag available on all platforms?

[Scott Byer, 2011/05/31 21:02:45]

Hmm, perhaps I'm being too cautious on the initial implementation. The intent is
to get this cross-platform, but the initial concentration is on CrOS. But you're
right, if someone doesn't want to see things break, they just don't set the
flag.

Done.

On 2011/05/31 20:40:24, darin wrote:

+        'feature_defines': [
+          'ENABLE_SMOOTH_SCROLLING=1',
+        ],
+      }],
     ],
     # TODO: If the need arises, create a mechanism that will intelligently
     # merge the lists rather than replace one with the other. This may
     # require changes in gyp.
   },
 
 }
 
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