Add the mips_dsp_rev build variable.

build/common.gypi

Index: build/common.gypi
diff --git a/build/common.gypi b/build/common.gypi
index 948dcece70dcd3ca0944135682591ff6440b9054..edc45b4e1df64bce33252239280b0650078194ab 100644
--- a/build/common.gypi
+++ b/build/common.gypi
@@ -184,6 +184,13 @@
         # below for MIPS targets.
         'mips_arch_variant%': '',
 
+        # MIPS DSP ASE revision. Possible values are:
+        #   0: unavailable
+        #   1: revision 1
+        #   2: revision 2
+        # Default: 0.
+        'mips_dsp_rev%': 0,
+
         'conditions': [
           # Ash needs Aura.
           ['use_aura==0', {
@@ -276,6 +283,7 @@
       'target_arch%': '<(target_arch)',
       'target_subarch%': '<(target_subarch)',
       'mips_arch_variant%': '<(mips_arch_variant)',
+      'mips_dsp_rev%': '<(mips_dsp_rev)',
       'toolkit_views%': '<(toolkit_views)',
       'desktop_linux%': '<(desktop_linux)',
       'use_aura%': '<(use_aura)',
@@ -1059,6 +1067,7 @@
     'target_arch%': '<(target_arch)',
     'target_subarch%': '<(target_subarch)',
     'mips_arch_variant%': '<(mips_arch_variant)',
+    'mips_dsp_rev%': '<(mips_dsp_rev)',
     'host_arch%': '<(host_arch)',
     'toolkit_views%': '<(toolkit_views)',
     'ui_compositor_image_transport%': '<(ui_compositor_image_transport)',
@@ -4066,6 +4075,12 @@
                   ['android_webview_build==0 and mips_arch_variant=="r1"', {
                     'cflags': ['-mips32', '-Wa,-mips32'],
                   }],
+                  ['android_webview_build==0 and mips_dsp_rev==1', {
+                    'cflags': ['-mdsp'],
+                  }],
+                  ['android_webview_build==0 and mips_dsp_rev==2', {
+                    'cflags': ['-mdspr2'],
+                  }],
                 ],
                 'ldflags': [
                   '-Wl,--no-keep-memory'