re-land increase of linker pool for android builder

This is re-land of
https://chromium-review.googlesource.com/894928

I changed to use cpu core for restriction and use lower memory limit only on
non-debug and non-sanitizer build.

I explained more detailed intention of my cl in
https://bugs.chromium.org/p/chromium/issues/detail?id=808582#c10


Bug: 808582, 804251
Change-Id: Ic98e9ffd7497a63c3aa98ec50b06f90c225d0107
Reviewed-on: https://chromium-review.googlesource.com/900611
Commit-Queue: Takuto Ikuta <tikuta@google.com>
Reviewed-by: agrieve <agrieve@chromium.org>
Cr-Original-Commit-Position: refs/heads/master@{#534637}
Cr-Mirrored-From: https://chromium.googlesource.com/chromium/src
Cr-Mirrored-Commit: 880379154e507eecff550d10feb1d8b8cc7e6ea2

toolchain/concurrent_links.gni

@@ -36,7 +36,13 @@ if (concurrent_links == -1) {
   } else if (is_mac) {
     _args = [ "--mem_per_link_gb=4" ]
   } else if (is_android && !is_component_build && symbol_level == 2) {
+    # Full debug symbols require large memory for link.
     _args = [ "--mem_per_link_gb=25" ]
+  } else if (is_android && !is_debug && !using_sanitizer && symbol_level == 1) {
+    # Increase the number of concurrent links for release bots. Debug builds
+    # make heavier use of ProGuard, and so should not be raised. Sanitizers also
+    # increase the memory overhead.
+    _args = [ "--mem_per_link_gb=4" ]
   } else if (is_linux && !is_chromeos && symbol_level == 1) {
     _args = [ "--mem_per_link_gb=3" ]
   } else {

toolchain/get_concurrent_links.py

@@ -5,6 +5,7 @@
 # This script computs the number of concurrent links we want to run in the build
 # as a function of machine spec. It's based on GetDefaultConcurrentLinks in GYP.
 
+import multiprocessing
 import optparse
 import os
 import re
@@ -59,7 +60,13 @@ def _GetDefaultConcurrentLinks(mem_per_link_gb, reserve_mem_gb):
   mem_total_bytes = max(0, mem_total_bytes - reserve_mem_gb * 2**30)
   num_concurrent_links = int(max(1, mem_total_bytes / mem_per_link_gb / 2**30))
   hard_cap = max(1, int(os.getenv('GYP_LINK_CONCURRENCY_MAX', 2**32)))
-  return min(num_concurrent_links, hard_cap)
+
+  try:
+    cpu_cap = multiprocessing.cpu_count()
+  except:
+    cpu_cap = 1
+
+  return min(num_concurrent_links, hard_cap, cpu_cap)
 
 
 def main():