Update gradle wrapper & gradle plugin.

Enables JDK 11 support.

Bug: None
Change-Id: I12ad7ea6ebc1e7453d59b825b39d2fc55046e5b7
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/182841
Reviewed-by: Mirko Bonadei <mbonadei@webrtc.org>
Commit-Queue: Sami Kalliomäki <sakal@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#32013}

DEPS

@@ -27,9 +27,9 @@ deps = {
     'https://chromium.googlesource.com/chromium/src/build@2841b2534425fe42de13eda326fbbb5951e6d014',
   'src/buildtools':
     'https://chromium.googlesource.com/chromium/src/buildtools@ff93f3ea1a7f033d3caf8f60ec1937cc71351419',
-  # Gradle 4.3-rc4. Used for testing Android Studio project generation for WebRTC.
+  # Gradle 6.6.1. Used for testing Android Studio project generation for WebRTC.
   'src/examples/androidtests/third_party/gradle': {
-    'url': 'https://chromium.googlesource.com/external/github.com/gradle/gradle.git@89af43c4d0506f69980f00dde78c97b2f81437f8',
+    'url': 'https://chromium.googlesource.com/external/github.com/gradle/gradle.git@f2d1fb54a951d8b11d25748e4711bec8d128d7e3',
     'condition': 'checkout_android',
   },
   'src/ios': {

examples/aarproject/app/build.gradle

@@ -2,7 +2,6 @@ apply plugin: 'com.android.application'
 
 android {
     compileSdkVersion 27
-    buildToolsVersion "27.0.1"
     defaultConfig {
         applicationId "org.appspot.apprtc"
         minSdkVersion 21

examples/aarproject/build.gradle

@@ -7,7 +7,7 @@ buildscript {
         jcenter()
     }
     dependencies {
-        classpath 'com.android.tools.build:gradle:3.0.0-beta2'
+        classpath 'com.android.tools.build:gradle:4.0.0'
 
 
         // NOTE: Do not place your application dependencies here; they belong