Add support for Mac/iOS application bundles to GN tool.

tools/gn/docs/reference.md

 # GN Reference
 
 *This page is automatically generated from* `gn help --markdown all`.
 
 ## **\--args**: Specifies build arguments overrides.
 
 ```
   See "gn help buildargs" for an overview of how build arguments work.
 
   Most operations take a build directory. The build arguments are taken
@@ skipping 1093 matching lines @@
     sources = [ "data1.dat", "data2.dat", "data3.dat" ]
 
     # Use source expansion to generate output files with the
     # corresponding file names in the gen dir. This will just copy each
     # file.
     outputs = [ "$target_gen_dir/{{source_file_part}}" ]
   }
 
 
 ```
+## **copy_bundle_data**: Declare a target that copy "bundle_data" files.
+
+```
+  Similar to the "copy" target, but the list of files to copy comes
+  from the "bundle_data" property of all dependencies recursively.
+  It can be used to copy files required at runtime by the application
+  into a location where it can be found.
+
+  This uses the "copy_bundle_data" tool from the toolchain.
+
+  See "gn help copy" for more information.
+
+```
+
+### **Examples**
+
+```
+  # A source_set that has a runtime dependency expressed as bundle_data
+  source_set("icu") {
+    sources = [ "icu.h", "icu.cc" ]
+    bundle_data = [ "icudtl.dat" ]
+  }
+
+  # Main application executable.
+  executable("app.app") {
+    visibility = [ ":app" ]
+    deps = [ ":icu" ]
+    output_name = "$root_build_dir/app.app/app"
+    sources = [ "main.cc" ]
+  }
+
+  # Copy runtime dependencies into the application bundle, filtering
+  # the .xcassets files as they need to be compiled into a .car file
+  # on Mac/iOS.
+  copy_bundle_data("app.bundle") {
+    visibility = [ ":app" ]
+    deps = [ ":icu" ]  # Same deps as the executable.
+    outputs = [ $root_build_dir/app.app/{{source_file_name}}" ]
+    bundle_data_filter = [ "*.xcassets" ]
+  }
+
+  # Main application target.
+  group("app") {
+    deps = [ ":app.app", "app.bundle" ]
+  }
+
+
+```
 ## **declare_args**: Declare build arguments.
 
 ```
   Introduces the given arguments into the current scope. If they are
   not specified on the command line or in a toolchain's arguments,
   the default values given in the declare_args block will be used.
   However, these defaults will not override command-line values.
 
   See also "gn help buildargs" for an overview.
 
@@ skipping 153 matching lines @@
 ## **executable**: Declare an executable target.
 
 ### **Variables**
 
 ```
   Flags: cflags, cflags_c, cflags_cc, cflags_objc, cflags_objcc,
          asmflags, defines, include_dirs, ldflags, lib_dirs, libs,
          precompiled_header, precompiled_source
   Deps: data_deps, deps, public_deps
   Dependent configs: all_dependent_configs, public_configs
-  General: check_includes, configs, data, inputs, output_name,
-           output_extension, public, sources, testonly, visibility
+  General: bundle_data, check_includes, configs, data, inputs,
+           output_name, output_extension, public, sources, testonly,
+           visibility
 
 
 ```
 ## **foreach**: Iterate over a list.
 
 ```
   foreach(<loop_var>, <list>) {
     <loop contents>
   }
 
@@ skipping 434 matching lines @@
 ```
 
 ### **Variables**
 
 ```
   Flags: cflags, cflags_c, cflags_cc, cflags_objc, cflags_objcc,
          asmflags, defines, include_dirs, ldflags, lib_dirs, libs,
          precompiled_header, precompiled_source
   Deps: data_deps, deps, public_deps
   Dependent configs: all_dependent_configs, public_configs
-  General: check_includes, configs, data, inputs, output_name,
-           output_extension, public, sources, testonly, visibility
+  General: bundle_data, check_includes, configs, data, inputs,
+           output_name, output_extension, public, sources, testonly,
+           visibility
 
 
 ```
 ## **print**: Prints to the console.
 
 ```
   Prints all arguments to the console separated by spaces. A newline is
   automatically appended to the end.
 
   This function is intended for debugging. Note that build files are run
@@ skipping 339 matching lines @@
 ```
 
 ### **Variables**
 
 ```
   Flags: cflags, cflags_c, cflags_cc, cflags_objc, cflags_objcc,
          asmflags, defines, include_dirs, ldflags, lib_dirs, libs,
          precompiled_header, precompiled_source
   Deps: data_deps, deps, public_deps
   Dependent configs: all_dependent_configs, public_configs
-  General: check_includes, configs, data, inputs, output_name,
-           output_extension, public, sources, testonly, visibility
+  General: bundle_data, check_includes, configs, data, inputs,
+           output_name, output_extension, public, sources, testonly,
+           visibility
 
 
 ```
 ## **source_set**: Declare a source set target.
 
 ```
   A source set is a collection of sources that get compiled, but are not
   linked to produce any kind of library. Instead, the resulting object
   files are implicitly added to the linker line of all targets that
   depend on the source set.
@@ skipping 19 matching lines @@
 ```
 
 ### **Variables**
 
 ```
   Flags: cflags, cflags_c, cflags_cc, cflags_objc, cflags_objcc,
          asmflags, defines, include_dirs, ldflags, lib_dirs, libs,
          precompiled_header, precompiled_source
   Deps: data_deps, deps, public_deps
   Dependent configs: all_dependent_configs, public_configs
-  General: check_includes, configs, data, inputs, output_name,
-           output_extension, public, sources, testonly, visibility
+  General: bundle_data, check_includes, configs, data, inputs,
+           output_name, output_extension, public, sources, testonly,
+           visibility
 
 
 ```
 ## **static_library**: Declare a static library target.
 
 ```
   Make a ".a" / ".lib" file.
 
   If you only need the static library for intermediate results in the
   build, you should consider a source_set instead since it will skip
   the (potentially slow) step of creating the intermediate library file.
 
 ```
 
 ### **Variables**
 
 ```
   Flags: cflags, cflags_c, cflags_cc, cflags_objc, cflags_objcc,
          asmflags, defines, include_dirs, ldflags, lib_dirs, libs,
          precompiled_header, precompiled_source
   Deps: data_deps, deps, public_deps
   Dependent configs: all_dependent_configs, public_configs
-  General: check_includes, configs, data, inputs, output_name,
-           output_extension, public, sources, testonly, visibility
+  General: bundle_data, check_includes, configs, data, inputs,
+           output_name, output_extension, public, sources, testonly,
+           visibility
 
 
 ```
 ## **target**: Declare an target with the given programmatic type.
 
 ```
   target(target_type_string, target_name_string) { ... }
 
   The target() function is a way to invoke a built-in target or template
   with a type determined at runtime. This is useful for cases where the
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      those configs appear in the list.
   5. all_dependent_configs pulled from dependencies, in the order of
      the "deps" list. This is done recursively. If a config appears
      more than once, only the first occurance will be used.
   6. public_configs pulled from dependencies, in the order of the
      "deps" list. If a dependency is public, they will be applied
      recursively.
 
 
 ```
+## **bundle_data**: Runtime data dependency (Mac/iOS).
+
+```
+  List files that are required at runtime by the current target and
+  should be copied into the application bundle.
+
+  See also "gn help copy_bundle_data".
+
+
+```
 ## **cflags***: Flags passed to the C compiler.
 
 ```
   A list of strings.
 
   "cflags" are passed to all invocations of the C, C++, Objective C,
   and Objective C++ compilers.
 
   To target one of these variants individually, use "cflags_c",
   "cflags_cc", "cflags_objc", and "cflags_objcc",
@@ skipping 52 matching lines @@
      those configs appear in the list.
   5. all_dependent_configs pulled from dependencies, in the order of
      the "deps" list. This is done recursively. If a config appears
      more than once, only the first occurance will be used.
   6. public_configs pulled from dependencies, in the order of the
      "deps" list. If a dependency is public, they will be applied
      recursively.
 
 
 ```
+## **bundle_data_filter**: Exclusions for copy_bundle_data.
+
+```
+  List of file patterns that need to be excluded from the application
+  bundle. All files matching this pattern will be excluded.
+
+  See also "gn help copy_bundle_data".
+
+
+```
 ## **cflags***: Flags passed to the C compiler.
 
 ```
   A list of strings.
 
   "cflags" are passed to all invocations of the C, C++, Objective C,
   and Objective C++ compilers.
 
   To target one of these variants individually, use "cflags_c",
   "cflags_cc", "cflags_objc", and "cflags_objcc",
@@ skipping 1785 matching lines @@
 **  -q**: Quiet mode. Don't print output on success.
 **  \--root**: Explicitly specify source root.
 **  \--runtime-deps-list-file**: Save runtime dependencies for targets in file.
 **  \--threads**: Specify number of worker threads.
 **  \--time**: Outputs a summary of how long everything took.
 **  \--tracelog**: Writes a Chrome-compatible trace log to the given file.
 **  -v**: Verbose logging.
 **  \--version**: Prints the GN version number and exits.
 
 ```