Rework approach to allowing extra flags for CrOS builds.

build/toolchain/gcc_toolchain.gni

Index: build/toolchain/gcc_toolchain.gni
diff --git a/build/toolchain/gcc_toolchain.gni b/build/toolchain/gcc_toolchain.gni
index eecb409a71c35d58e5461b356139785fa1d82bba..428f27427d5f0dd80cf2b7f5c94d6f9027b53d7a 100644
--- a/build/toolchain/gcc_toolchain.gni
+++ b/build/toolchain/gcc_toolchain.gni
@@ -21,18 +21,6 @@ import("//build/toolchain/toolchain.gni")
 #
 # Optional parameters that control the tools:
 #
-#  - extra_cflags
-#      Extra flags to be appended when compiling C files (but not C++ files).
-#  - extra_cppflags
-#      Extra flags to be appended when compiling both C and C++ files. "CPP"
-#      stands for "C PreProcessor" in this context, although it can be
-#      used for non-preprocessor flags as well. Not to be confused with
-#      "CXX" (which follows).
-#  - extra_cxxflags
-#      Extra flags to be appended when compiling C++ files (but not C files).
-#  - extra_ldflags
-#      Extra flags to be appended when linking
-#
 #  - libs_section_prefix
 #  - libs_section_postfix
 #      The contents of these strings, if specified, will be placed around
@@ -188,30 +176,6 @@ template("gcc_toolchain") {
       solink_libs_section_postfix = ""
     }
 
-    if (defined(invoker.extra_cflags) && invoker.extra_cflags != "") {
-      extra_cflags = " " + invoker.extra_cflags
-    } else {
-      extra_cflags = ""
-    }
-
-    if (defined(invoker.extra_cppflags) && invoker.extra_cppflags != "") {
-      extra_cppflags = " " + invoker.extra_cppflags
-    } else {
-      extra_cppflags = ""
-    }
-
-    if (defined(invoker.extra_cxxflags) && invoker.extra_cxxflags != "") {
-      extra_cxxflags = " " + invoker.extra_cxxflags
-    } else {
-      extra_cxxflags = ""
-    }
-
-    if (defined(invoker.extra_ldflags) && invoker.extra_ldflags != "") {
-      extra_ldflags = " " + invoker.extra_ldflags
-    } else {
-      extra_ldflags = ""
-    }
-
     # These library switches can apply to all tools below.
     lib_switch = "-l"
     lib_dir_switch = "-L"
@@ -221,7 +185,7 @@ template("gcc_toolchain") {
 
     tool("cc") {
       depfile = "{{output}}.d"
-      command = "$cc -MMD -MF $depfile ${rebuild_string}{{defines}} {{include_dirs}} {{cflags}} {{cflags_c}}${extra_cppflags}${extra_cflags} -c {{source}} -o {{output}}"
+      command = "$cc -MMD -MF $depfile ${rebuild_string}{{defines}} {{include_dirs}} {{cflags}} {{cflags_c}} -c {{source}} -o {{output}}"
       depsformat = "gcc"
       description = "CC {{output}}"
       outputs = [
@@ -231,7 +195,7 @@ template("gcc_toolchain") {
 
     tool("cxx") {
       depfile = "{{output}}.d"
-      command = "$cxx -MMD -MF $depfile ${rebuild_string}{{defines}} {{include_dirs}} {{cflags}} {{cflags_cc}}${extra_cppflags}${extra_cxxflags} -c {{source}} -o {{output}}"
+      command = "$cxx -MMD -MF $depfile ${rebuild_string}{{defines}} {{include_dirs}} {{cflags}} {{cflags_cc}} -c {{source}} -o {{output}}"
       depsformat = "gcc"
       description = "CXX {{output}}"
       outputs = [
@@ -290,7 +254,7 @@ template("gcc_toolchain") {
       # .TOC file, overwrite it, otherwise, don't change it.
       tocfile = sofile + ".TOC"
 
-      link_command = "$ld -shared {{ldflags}}${extra_ldflags} -o \"$unstripped_sofile\" -Wl,-soname=\"$soname\" @\"$rspfile\""
+      link_command = "$ld -shared {{ldflags}} -o \"$unstripped_sofile\" -Wl,-soname=\"$soname\" @\"$rspfile\""
 
       assert(defined(readelf), "to solink you must have a readelf")
       assert(defined(nm), "to solink you must have an nm")
@@ -351,7 +315,7 @@ template("gcc_toolchain") {
         unstripped_sofile = sofile
       }
 
-      command = "$ld -shared {{ldflags}}${extra_ldflags} -o \"$unstripped_sofile\" -Wl,-soname=\"$soname\" @\"$rspfile\""
+      command = "$ld -shared {{ldflags}} -o \"$unstripped_sofile\" -Wl,-soname=\"$soname\" @\"$rspfile\""
 
       if (defined(invoker.strip)) {
         strip_command = "${invoker.strip} --strip-unneeded -o \"$sofile\" \"$unstripped_sofile\""
@@ -403,7 +367,7 @@ template("gcc_toolchain") {
         unstripped_outfile = "{{root_out_dir}}/exe.unstripped/$exename"
       }
 
-      command = "$ld {{ldflags}}${extra_ldflags} -o \"$unstripped_outfile\" -Wl,--start-group @\"$rspfile\" {{solibs}} -Wl,--end-group $libs_section_prefix {{libs}} $libs_section_postfix"
+      command = "$ld {{ldflags}} -o \"$unstripped_outfile\" -Wl,--start-group @\"$rspfile\" {{solibs}} -Wl,--end-group $libs_section_prefix {{libs}} $libs_section_postfix"
       if (defined(invoker.strip)) {
         link_wrapper =
             rebase_path("//build/toolchain/gcc_link_wrapper.py", root_build_dir)