Add retrolambda.py and integrate it to build process.

build/config/android/config.gni

Index: build/config/android/config.gni
diff --git a/build/config/android/config.gni b/build/config/android/config.gni
index 0da122dd836f48787a20d2c159330f4a234482c1..ded55d9070340ddb372399e13ec44dcacaad943c 100644
--- a/build/config/android/config.gni
+++ b/build/config/android/config.gni
@@ -136,7 +136,7 @@ if (is_android) {
     # Required for Android M+ due to SELinux policies (stronger sandboxing).
     disable_incremental_isolated_processes = false
 
-    # Speed up incremental compiles by compiling only changed files.
+    # Speeds up incremental compiles by compiling only changed files.
     enable_incremental_javac = false
 
     # Adds intrumentation to each function. Writes a file with the order that
@@ -146,6 +146,9 @@ if (is_android) {
     # Builds secondary abi for APKs, supports build 32-bit arch as secondary
     # abi in 64-bit Monochrome and WebView.
     build_apk_secondary_abi = true
+
+    # Enables java8 language features (via retrolambda).

[agrieve, 2016/11/30 21:54:42]

nit: please add "work-in-progress (http://crbug.com/642600)"

[F, 2016/12/01 15:09:51]

Done.

+    use_java8 = false
   }
 
   # We need a second declare_args block to make sure we are using the overridden