[GN]: Precompiled header support for GCC.

build/toolchain/mac/BUILD.gn

Index: build/toolchain/mac/BUILD.gn
diff --git a/build/toolchain/mac/BUILD.gn b/build/toolchain/mac/BUILD.gn
index 80d782f47f9698c3749c751e0f34c46a39015e17..6a727e6124ebb2824c3ca58a0466708b2244e733 100644
--- a/build/toolchain/mac/BUILD.gn
+++ b/build/toolchain/mac/BUILD.gn
@@ -50,6 +50,10 @@ template("mac_toolchain") {
 
     tool("cc") {
       depfile = "{{output}}.d"
+
+      # TODO:(andybons): enable this when GCC PCH support in the binary has been
+      # rolled.
+      #precompiled_header_type = "gcc"
       command = "$cc -MMD -MF $depfile {{defines}} {{include_dirs}} {{cflags}} {{cflags_c}} -c {{source}} -o {{output}}"
       depsformat = "gcc"
       description = "CC {{output}}"
@@ -60,6 +64,10 @@ template("mac_toolchain") {
 
     tool("cxx") {
       depfile = "{{output}}.d"
+
+      # TODO:(andybons): enable this when GCC PCH support in the binary has been
+      # rolled.
+      #precompiled_header_type = "gcc"
       command = "$cxx -MMD -MF $depfile {{defines}} {{include_dirs}} {{cflags}} {{cflags_cc}} -c {{source}} -o {{output}}"
       depsformat = "gcc"
       description = "CXX {{output}}"
@@ -82,6 +90,11 @@ template("mac_toolchain") {
     tool("objc") {
       depfile = "{{output}}.d"
       command = "$cxx -MMD -MF $depfile {{defines}} {{include_dirs}} {{cflags}} {{cflags_objc}} -c {{source}} -o {{output}}"
+
+      # TODO:(andybons): enable this when GCC PCH support in the binary has been
+      # rolled.
+      #precompiled_header_type = "gcc"
+      command = "$cxx -MMD -MF $depfile {{defines}} {{include_dirs}} {{cflags}} {{cflags_c}} {{cflags_objc}} -c {{source}} -o {{output}}"
       depsformat = "gcc"
       description = "OBJC {{output}}"
       outputs = [
@@ -92,6 +105,10 @@ template("mac_toolchain") {
     tool("objcxx") {
       depfile = "{{output}}.d"
       command = "$cxx -MMD -MF $depfile {{defines}} {{include_dirs}} {{cflags}} {{cflags_objcc}} -c {{source}} -o {{output}}"
+
+      # TODO:(andybons): enable this when GCC PCH support in the binary has been
+      # rolled.
+      #precompiled_header_type = "gcc"
       depsformat = "gcc"
       description = "OBJCXX {{output}}"
       outputs = [