Roll Chrome into Mojo.

build/config/compiler/BUILD.gn

Index: build/config/compiler/BUILD.gn
diff --git a/build/config/compiler/BUILD.gn b/build/config/compiler/BUILD.gn
index cc2b7f55922bdd465896eeae06da6ff773e17423..164b97d26260f3e238834c36ffad1e9e53037f5c 100644
--- a/build/config/compiler/BUILD.gn
+++ b/build/config/compiler/BUILD.gn
@@ -350,10 +350,7 @@ config("compiler") {
       "-Wl,-z,now",
       "-Wl,-z,relro",
     ]
-
-    # TODO(zork): The mipsel build is broken in ffmpeg, guard this flag for now
-    # to hide the breakage. https://crbug.com/450771
-    if (!using_sanitizer && cpu_arch != "mipsel") {
+    if (!using_sanitizer) {
       ldflags += [ "-Wl,-z,defs" ]
     }
   }
@@ -903,7 +900,17 @@ if (is_win) {
     "/Oy-",  # disable omitting frame pointers, must be after /o2.
     "/Os",  # favor size over speed.
   ]
-  common_optimize_on_ldflags = []
+  if (!is_asan) {
+    common_optimize_on_cflags += [
+      # Put data in separate COMDATs. This allows the linker
+      # to put bit-identical constants at the same address even if
+      # they're unrelated constants, which saves binary size.
+      # This optimization can't be used when ASan is enabled because
+      # it is not compatible with the ASan ODR checker.
+      "/Gw",
+    ]
+  }
+  common_optimize_on_ldflags = [ "/OPT:REF" ]
 } else {
   common_optimize_on_cflags = [
     # Don't emit the GCC version ident directives, they just end up in the
@@ -938,9 +945,15 @@ if (is_win) {
       # Specifically tell the linker to perform optimizations.
       # See http://lwn.net/Articles/192624/ .
       "-Wl,-O1",
-      "-Wl,--as-needed",
       "-Wl,--gc-sections",
     ]
+
+    if (!using_sanitizer) {
+      # Functions interposed by the sanitizers can make ld think
+      # that some libraries aren't needed when they actually are,
+      # http://crbug.com/234010. As workaround, disable --as-needed.
+      common_optimize_on_ldflags += [ "-Wl,--as-needed" ]
+    }
   }
 }