Hook up ARM architecture flags to GN build.

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 ce0aae7afb72d0def54b1ec6b0713cd0c197d5bc..44bc05bcc1be7c8b2e26eb798b14ddaf723528e8 100644
--- a/build/config/compiler/BUILD.gn
+++ b/build/config/compiler/BUILD.gn
@@ -4,6 +4,9 @@
 
 import("//build/config/android/config.gni")
 import("//build/config/sysroot.gni")
+if (cpu_arch == "arm") {
+  import("//build/config/arm.gni")
+}
 
 # compiler ---------------------------------------------------------------------
 #
@@ -100,6 +103,25 @@ config("compiler") {
     } else if (cpu_arch == "x86") {
       cflags += "-m32"
       ldflags += "-m32"
+    } else if (cpu_arch == "arm") {
+      # Don't set the compiler flags for the WebView build. These will come
+      # from the Android build system.
+      if (!is_android_webview_build) {
+        cflags += [
+          "-march=$arm_arch",
+          "-mfpu=$arm_fpu",
+          "-mfloat_abi=$arm_float_abi",
+        ]
+        if (arm_tune != "") {
+          cflags += "-mtune=$arm_tune"

[scottmg, 2014/01/13 23:47:20]

[ ] around here like below?

[brettw, 2014/01/13 23:50:22]

Thanks, I'm trying to be consistent about this. Do you think I should change the
language syntax to disallow list + string to eliminate this option?

[scottmg, 2014/01/13 23:56:55]

Yes, I think that'd be a good idea. It sort of seems nice at first, but I think
it ends up being a bit confusing and you end up reading it multiple times,
especially if you're not sure what the type of the LHS is.

+        }
+        if (arm_use_thumb) {
+          cflags += [ "-mthumb" ]
+          if (is_android) {
+            cflags += [ "-mthumb_interwork" ]
+          }
+        }
+      }
     }
 
     defines += [ "_FILE_OFFSET_BITS=64" ]