[Android] Add gyp support for multidex.

base/base.gyp

Index: base/base.gyp
diff --git a/base/base.gyp b/base/base.gyp
index e9b09959da833589caffca378e963d4192989c5e..25047e0761f8fa3e46b4160295a673cdcb9878ee 100644
--- a/base/base.gyp
+++ b/base/base.gyp
@@ -1440,6 +1440,7 @@
             'base_java_library_process_type',
             'base_java_memory_pressure_level',
             'base_native_libraries_gen',
+            '../third_party/android_tools/android_tools.gyp:android_support_multidex_javalib',
             '../third_party/jsr-305/jsr-305.gyp:jsr_305_javalib',
           ],
           'includes': [ '../build/java.gypi' ],
@@ -1490,6 +1491,7 @@
           'dependencies': [
             'base_java',
             '../testing/android/on_device_instrumentation.gyp:reporter_java',
+            '../third_party/android_tools/android_tools.gyp:android_support_multidex_javalib',
           ],
           'variables': {
             'java_in_dir': '../base/test/android/javatests',