Limit heap size of when running R8 / D8

Adds -Xmx1G to limit heap size to 1GB.

My local test of R8 on MonochromePublic.aab had a peak RSS
of 1.8GB with this flag and 8GB without it.

Does not seem to cause the command to run measurably slower.

I found that the r8 wrapper script in AOSP uses this same flag and
so does the Android lint wrapper script.

Bug: 1098333
Change-Id: Icca79bf6c1e9c8f003f613c178983f63cf9fbf04
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2348018
Commit-Queue: Sam Maier <smaier@chromium.org>
Auto-Submit: Andrew Grieve <agrieve@chromium.org>
Reviewed-by: Sam Maier <smaier@chromium.org>
Cr-Commit-Position: refs/heads/master@{#796806}

build/android/gyp/dex.py

@@ -474,6 +474,7 @@ def _OnStaleMd5(changes, options, final_dex_inputs, dex_cmd):
 def MergeDexForIncrementalInstall(r8_jar_path, src_paths, dest_dex_jar):
   dex_cmd = [
       build_utils.JAVA_PATH,
+      '-Xmx1G',
       '-cp',
       r8_jar_path,
       'com.android.tools.r8.D8',
@@ -510,6 +511,7 @@ def main(args):
 
   dex_cmd = [
       build_utils.JAVA_PATH,
+      '-Xmx1G',
       '-cp',
       options.r8_jar_path,
       'com.android.tools.r8.D8',

build/android/gyp/dex_jdk_libs.py

@@ -38,6 +38,7 @@ def DexJdkLibJar(r8_path, min_api, desugar_jdk_libs_json, desugar_jdk_libs_jar,
   with build_utils.TempDir() as tmp_dir:
     cmd = [
         build_utils.JAVA_PATH,
+        '-Xmx1G',
         '-cp',
         r8_path,
         'com.android.tools.r8.L8',

build/android/gyp/main_dex_list.py

@@ -56,6 +56,7 @@ def main():
   args = _ParseArgs()
   proguard_cmd = [
       build_utils.JAVA_PATH,
+      '-Xmx1G',
       '-cp',
       args.r8_path,
       'com.android.tools.r8.R8',

build/android/gyp/proguard.py

@@ -256,6 +256,7 @@ def _OptimizeWithR8(options,
     if options.disable_outlining:
       cmd += [' -Dcom.android.tools.r8.disableOutlining=1']
     cmd += [
+        '-Xmx1G',
         '-cp',
         options.r8_path,
         'com.android.tools.r8.R8',