Only enable the sse2 flags when building Chromium

build/common.gypi

Index: build/common.gypi
diff --git a/build/common.gypi b/build/common.gypi
index e0fba3422ea01d162fee02f7e462b66e8bafe74e..3219a269a6f8b40e401451586cd2ac2efc44cf25 100644
--- a/build/common.gypi
+++ b/build/common.gypi
@@ -302,12 +302,18 @@
             # used during computation does not change depending on how the
             # compiler optimized the code, since the value is always kept
             # in its specified precision.
+            'conditions': [
+              ['branding=="Chromium"', {
+                'cflags': [
+                  '-march=pentium4',
+                  '-msse2',
+                  '-mfpmath=sse',
+                ],
+              }],
+            ],
             'cflags': [
               '-m32',
-              '-march=pentium4',
               '-fno-exceptions',
-              '-msse2',
-              '-mfpmath=sse',
               '-Wall',
             ],
             'ldflags': [