Android: Update gradle versions for generate_gradle.py

Also adds distributionUrl=, which my Android Studio told me is now
necessary :/

Also enables warnings via gradle.properties. Without this, I just get
a warning saying:
  "There was a warning, but to see it you need to enable warnings".

Bug: None
Change-Id: I7064ee3a82666866a56d2d69e04563fb7c7e44d0
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2216323
Commit-Queue: Andrew Grieve <agrieve@chromium.org>
Reviewed-by: Peter Wen <wnwen@chromium.org>
Cr-Commit-Position: refs/heads/master@{#772373}

build/android/gradle/generate_gradle.py

@@ -527,11 +527,35 @@ def _CreateJniLibsDir(output_dir, entry_output_dir, so_files):
 
 
 def _GenerateLocalProperties(sdk_dir):
-  """Returns the data for project.properties as a string."""
+  """Returns the data for local.properties as a string."""
   return '\n'.join([
       '# Generated by //build/android/gradle/generate_gradle.py',
       'sdk.dir=%s' % sdk_dir,
-      ''])
+      '',
+  ])
+
+
+def _GenerateGradleWrapperPropertiesCanary():
+  """Returns the data for gradle-wrapper.properties as a string."""
+  # Before May 2020, this wasn't necessary. Might not be necessary at some point
+  # in the future?
+  return '\n'.join([
+      '# Generated by //build/android/gradle/generate_gradle.py',
+      ('distributionUrl=https\\://services.gradle.org/distributions/'
+       'gradle-6.4-rc-2-all.zip\n'),
+      '',
+  ])
+
+
+def _GenerateGradleProperties():
+  """Returns the data for gradle.properties as a string."""
+  return '\n'.join([
+      '# Generated by //build/android/gradle/generate_gradle.py',
+      '',
+      '# Tells Gradle to show warnings during project sync.',
+      'org.gradle.warning.mode=all',
+      '',
+  ])
 
 
 def _GenerateBaseVars(generator, build_vars):
@@ -930,6 +954,15 @@ def main():
   _WriteFile(
       os.path.join(generator.project_dir, 'local.properties'),
       _GenerateLocalProperties(args.sdk_path))
+  _WriteFile(os.path.join(generator.project_dir, 'gradle.properties'),
+             _GenerateGradleProperties())
+
+  wrapper_properties = os.path.join(generator.project_dir, 'gradle', 'wrapper',
+                                    'gradle-wrapper.properties')
+  if os.path.exists(wrapper_properties):
+    os.unlink(wrapper_properties)
+  if args.canary:
+    _WriteFile(wrapper_properties, _GenerateGradleWrapperPropertiesCanary())
 
   zip_tuples = []
   generated_inputs = set()

build/android/gradle/root.jinja

@@ -16,11 +16,11 @@ buildscript {
     }
     dependencies {
 {% if channel == 'canary' %}
-        classpath "com.android.tools.build:gradle:4.0.0-alpha04"
+        classpath "com.android.tools.build:gradle:4.1.0-alpha09"
 {% elif channel == 'beta' %}
-        classpath "com.android.tools.build:gradle:3.1.0-beta4"
+        classpath "com.android.tools.build:gradle:4.0.0-rc01"
 {% else %}
-        classpath "com.android.tools.build:gradle:3.0.1"
+        classpath "com.android.tools.build:gradle:3.6.3"
 {% endif %}
     }
 }