build full 64bit WebView

build/config/android/config.gni

 # Copyright 2014 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 # This file contains common system config stuff for the Android build.
 
 if (is_android) {
   assert(rebase_path("//", root_build_dir) == "../../",
          "Android output directory must be nested 2 levels within src/ (" +
              "e.g.: out-gn/Debug). http://crbug.com/412935")
@@ skipping 115 matching lines @@
     # Disables process isolation when building _incremental targets.
     # Required for Android M+ due to SELinux policies (stronger sandboxing).
     disable_incremental_isolated_processes = false
 
     # Speed up incremental compiles by compiling only changed files.
     enable_incremental_javac = false
 
     # Adds intrumentation to each function. Writes a file with the order that
     # functions are called at startup.
     use_order_profiling = false
+
+    # Only build 64-bit binaries in 64-bit WebView APK. 32-bit apps will not be
+    # supported; for development only.
+    build_64bit_only_webview = false

[jbudorick, 2016/09/16 16:23:35]

As this is webview-specific, it seems like it should be handled by a .gni in
android_webview rather than in here.

[Torne, 2016/09/16 16:37:57]

It'll also have an effect on the monochrome APK.

[michaelbai, 2016/09/16 20:05:55]

Since there are 2 separated variable, this one is webview specific, moved it to
android_webview

   }
 
   # We need a second declare_args block to make sure we are using the overridden
   # value of the arguments set above.
   declare_args() {
     # Speed up dexing using dx --incremental.
     enable_incremental_dx = is_java_debug
   }
 
+  if (defined(merge_64bit_webview_and_monochrome) &&

[jbudorick, 2016/09/16 16:23:35]

I agree with torne -- this should be defined upstream.

+      merge_64bit_webview_and_monochrome) {
+    build_64bit_only_webview = true
+  }
+
   # Neither of these should ever be used for release builds since they are
   # somewhat experimental and dx --incremental is known to not produce
   # byte-for-byte identical output.
   assert(!(enable_incremental_dx && !is_java_debug))
   assert(!(enable_incremental_javac && !is_java_debug))
 
   # Host stuff -----------------------------------------------------------------
 
   # Defines the name the Android build gives to the current host CPU
   # architecture, which is different than the names GN uses.
@@ skipping 169 matching lines @@
           "//build/toolchain/android:${android_secondary_abi_cpu}"
     }
   }
 }
 
 declare_args() {
   # Enables used resource whitelist generation. Set for official builds only
   # as a large amount of build output is generated.
   enable_resource_whitelist_generation = is_android && is_official_build
 }