GN: add a helper script for running Android builds

Think of this as the spiritual equivalent of platform_tools/android/bin/android_run_skia, but for GN and easier to type.

Cutting down the debug symbols makes Android builds about 1/4 the size.

BUG=skia:
GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2323833002
DOCS_PREVIEW= https://skia.org/user/quick/gn?cl=2323833002

Review-Url: https://codereview.chromium.org/2323833002

bin/droid

@@ -0,0 +1,20 @@
+#!/bin/bash
+
+# Run a GN-built Android binary on the connected device.
+#
+# Example usage:
+#  $ ninja -C out dm
+#  $ droid out/dm --src gm --config gpu
+#
+# See https://skia.org/user/quick/gn for build instructions.
+
+path=$1
+name=$(basename $1)
+shift
+args=$@
+
+set -e
+set -x
+
+adb push $path resources /data/local/tmp/
+adb shell "cd /data/local/tmp; ./$name $args"

gn/BUILD.gn

@@ -31,7 +31,6 @@ config("no_rtti") {
 config("default") {
   cflags = [
     "-O1",
-    "-g",
     "-fstrict-aliasing",
     "-fPIC",
     "-fvisibility=hidden",
@@ -57,6 +56,14 @@ config("default") {
   ]
   ldflags = []
 
+  # It's annoying to wait for full debug symbols to push over
+  # to Android devices.  -gline-tables-only is a lot slimmer.
+  if (is_android) {
+    cflags += [ "-gline-tables-only" ]
+  } else {
+    cflags += [ "-g" ]
+  }
+
   if (current_cpu == "arm") {
     cflags += [
       "-march=armv7-a",

site/user/quick/gn.md

@@ -74,3 +74,10 @@ desired `target_cpu`:
     gn gen out/x86      --args='ndk="/tmp/ndk" target_cpu="x86"'
 
 Other arguments like `is_debug` and `is_component_build` continue to work.
+
+To test on a locally connected Android device, you can use our `droid` convenience script:
+
+<!--?prettify lang=sh?-->
+
+    ninja -C out/arm64
+    bin/droid out/arm64/dm --src gm --config gpu