Refactor language detection logic to allow non-static CLD data sources.

third_party/cld_2/cld_2.gyp

Index: third_party/cld_2/cld_2.gyp
diff --git a/third_party/cld_2/cld_2.gyp b/third_party/cld_2/cld_2.gyp
index 6cda4028eadb91ad20f661c0e17b19b7023e001f..a27f7a40e9aaaa4884b4b42468cc76bd30ddb3de 100644
--- a/third_party/cld_2/cld_2.gyp
+++ b/third_party/cld_2/cld_2.gyp
@@ -22,51 +22,76 @@
     ],
   },
   'variables': {
+    # This variable controls which dependency is resolved by the pass-through
+    # target 'cld2_platform_impl', and allows the embedder to choose which
+    # kind of CLD2 support is required at build time:
+    #
+    # - If the value is 'static', then the cld2_platform_impl target will depend
+    #   upon the cld2_static target
+    # - If the value is 'dynamic', then the cld2_platform_impl target will
+    #   depend upon the cld2_dynamic target.
+    #
+    # High-level targets for Chromium unit tests hard-code a dependency upon
+    # cld2_static because doing so makes sense for use cases that aren't
+    # affected by the loading of language detection data; however, most other
+    # targets (e.g. the final executables and interactive UI tests) should be
+    # linked against whatever the embedder needs.
+    #
+    # Maintainers:
+    # This value may be reasonably tweaked in a 'conditions' block below on a
+    # per-platform basis. Don't forget to update the expectations in
+    # components/translate/content/browser/browser_cld_utils.cc as well, to
+    # match whatever is done here.
+    'cld2_platform_support%': 'static',
+
     # These sources need to be included in both static and dynamic builds as
     # well as the dynamic data tool.
     'cld2_core_sources': [
       'src/internal/cld2tablesummary.h',
-      'src/internal/cldutil.cc',
       'src/internal/cldutil.h',
-      'src/internal/cldutil_shared.cc',
       'src/internal/cldutil_shared.h',
-      'src/internal/compact_lang_det.cc',
-      'src/internal/compact_lang_det_hint_code.cc',
       'src/internal/compact_lang_det_hint_code.h',
-      'src/internal/compact_lang_det_impl.cc',
       'src/internal/compact_lang_det_impl.h',
       'src/internal/debug.h',
-      'src/internal/debug_empty.cc',
-      'src/internal/fixunicodevalue.cc',
       'src/internal/fixunicodevalue.h',
-      'src/internal/generated_distinct_bi_0.cc',
-      'src/internal/generated_entities.cc',
-      'src/internal/generated_language.cc',
       'src/internal/generated_language.h',
-      'src/internal/generated_ulscript.cc',
       'src/internal/generated_ulscript.h',
-      'src/internal/getonescriptspan.cc',
       'src/internal/getonescriptspan.h',
       'src/internal/integral_types.h',
-      'src/internal/lang_script.cc',
       'src/internal/lang_script.h',
       'src/internal/langspan.h',
-      'src/internal/offsetmap.cc',
       'src/internal/offsetmap.h',
       'src/internal/port.h',
-      'src/internal/scoreonescriptspan.cc',
       'src/internal/scoreonescriptspan.h',
       'src/internal/stringpiece.h',
-      'src/internal/tote.cc',
       'src/internal/tote.h',
       'src/internal/utf8prop_lettermarkscriptnum.h',
       'src/internal/utf8repl_lettermarklower.h',
       'src/internal/utf8scannot_lettermarkspecial.h',
-      'src/internal/utf8statetable.cc',
       'src/internal/utf8statetable.h',
       'src/public/compact_lang_det.h',
       'src/public/encodings.h',
     ],
+    'cld2_core_impl_sources': [
+      # Compilation is dependent upon flags.
+      'src/internal/cldutil.cc',
+      'src/internal/cldutil_shared.cc',
+      'src/internal/compact_lang_det.cc',
+      'src/internal/compact_lang_det_hint_code.cc',
+      'src/internal/compact_lang_det_impl.cc',
+      'src/internal/debug_empty.cc',
+      'src/internal/fixunicodevalue.cc',
+      'src/internal/generated_distinct_bi_0.cc',
+      'src/internal/generated_entities.cc',
+      'src/internal/generated_language.cc',
+      'src/internal/generated_ulscript.cc',
+      'src/internal/getonescriptspan.cc',
+      'src/internal/lang_script.cc',
+      'src/internal/offsetmap.cc',
+      'src/internal/scoreonescriptspan.cc',
+      'src/internal/tote.cc',
+      'src/internal/utf8statetable.cc',
+    ],
     'cld2_dynamic_data_loader_sources': [
       'src/internal/cld2_dynamic_data.h',
       'src/internal/cld2_dynamic_data.cc',
@@ -104,26 +129,35 @@
       'sources': [
         # Note: sources list duplicated in GN build.
         '<@(cld2_core_sources)',
+        '<@(cld2_core_impl_sources)',
         '<@(cld2_data_sources)',
         '<@(cld2_dynamic_data_loader_sources)',
         'src/internal/cld2_dynamic_data_extractor.h',
         'src/internal/cld2_dynamic_data_extractor.cc',
         'src/internal/cld2_dynamic_data_tool.cc',
       ],
+      'defines': ['CLD2_DYNAMIC_MODE'],
     },
 
     {
       # GN version: //third_party/cld_2
+      # Depending upon cld_2 will provide core headers and function definitions,
+      # but no data. You must also depend on one of the following two targets:
+      # cld2_static - for a statically-linked data set built into the executable
+      # cld2_dynamic - for a dynamic data set loaded at runtime
       'target_name': 'cld_2',
       'type': 'static_library',
-      'sources': [],
+      'sources': ['<@(cld2_core_sources)'],
       'dependencies': [],
-      'conditions': [
-        ['cld2_data_source=="static"',
-          {'dependencies': ['cld2_static']},
-          {'dependencies': ['cld2_dynamic']}
-        ],
-      ],
+    },
+
+    # As described above in the comments for cld2_platform_support, this is a
+    # passthrough target that allows high-level targets to depend upon the same
+    # CLD support as desired by the embedder.
+    {
+      'target_name': 'cld2_platform_impl',
+      'type': 'none',
+      'dependencies': ['cld2_<(cld2_platform_support)'],
     },
 
     {
@@ -136,6 +170,7 @@
       ],
       'sources': [
         '<@(cld2_core_sources)',
+        '<@(cld2_core_impl_sources)',
         '<@(cld2_data_sources)',
       ],
     },
@@ -150,12 +185,10 @@
       ],
       'sources': [
         '<@(cld2_core_sources)',
+        '<@(cld2_core_impl_sources)',
         '<@(cld2_dynamic_data_loader_sources)',
       ],
       'defines': ['CLD2_DYNAMIC_MODE'],
-      'all_dependent_settings': {
-        'defines': ['CLD2_DYNAMIC_MODE'],
-      },
     },
   ],
 }