media: Build vector_math.cc with max optimization

It was currently built at "optimize for size", which means important
function such as FMAC_C weren't getting autovectorized and unrolled.
Since this file is performance sensitive, using max optimization seems
reasonable.

BUG=750923

Change-Id: Id38e66365ee1b8b636e391ba07b83a804142eba1
Reviewed-on: https://chromium-review.googlesource.com/597017Reviewed-by: Dale Curtis <dalecurtis@chromium.org>
Reviewed-by: Nico Weber <thakis@chromium.org>
Commit-Queue: Nico Weber <thakis@chromium.org>
Cr-Commit-Position: refs/heads/master@{#491372}

media/BUILD.gn

@@ -498,6 +498,10 @@ component("shared_memory_support") {
     ":media_config",
     ":media_implementation",
   ]
+  if (!is_debug) {
+    configs -= [ "//build/config/compiler:default_optimization" ]
+    configs += [ "//build/config/compiler:optimize_max" ]
+  }
   deps = [
     "//base",
     "//ui/gfx/geometry",