Add the mips_dsp_rev build variable.

build/config/mips.gni

Index: build/config/mips.gni
diff --git a/build/config/mips.gni b/build/config/mips.gni
index f544d9452284276f3f35d6ad789f33af639cb864..121ee8903ef632c09e81ed163f53e886d9131638 100644
--- a/build/config/mips.gni
+++ b/build/config/mips.gni
@@ -18,3 +18,25 @@ if (cpu_arch == "mipsel") {
     }
   }
 }
+
+if (cpu_arch == "mipsel") {
+  declare_args() {
+    # MIPS DSP ASE revision. Possible values are:

[kjellander_chromium, 2015/02/23 13:22:35]

move there three variables into the already existing declare_args block, at line
8.

[wtc, 2015/02/23 20:15:51]

I intend to dedicate the if-else-if block on lines 5-20 to the mips_arch_variant
build variable because that build variable has different default values in
various cases.

Please let me know if you prefer that I move the other build variable
declarations to that if-else-if block. I am very open-minded about this, so
please feel free to tell me!

[kjellander_chromium, 2015/02/25 21:08:07]

I personally prefer not duplicating code, so I would move this up, but I'll
leave it to you (or another reviewer) to decide.

[wtc, 2015/02/27 05:57:19]

Done. Please let me know if you want me to tweak the results.

+    #   0: unavailable
+    #   1: revision 1
+    #   2: revision 2
+    # Default: 0.

[brettw, 2015/02/23 18:51:36]

You don't have to write the default in the comment. The next line lists the
default so people reading the code will know, and GN will tell you the default
in "gn args --list"

[wtc, 2015/02/23 20:15:51]

Done.

+    mips_dsp_rev = 0
+
+    # MIPS floating-point ABI. Possible values are:
+    #   "hard"
+    #   "soft"
+    mips_float_abi = "hard"
+
+    # MIPS32 floating-point register width. Possible values are:
+    #   "fp32"
+    #   "fp64"
+    #   "fpxx"
+    mips_fpu_mode = "fp32"
+  }
+}