Android: Basic support for C++ in Android Studio

Add a new flag for generate_gradle.py, --native-target <gn target name>.
This allows C++ editing when --all is either passed or implicit (by
default). Starting with --native-target //chrome/android:monochrome in
Android Studio Canary (3.2) will result in most of the C++ files being
indexed and available both via the Android project view as well as the
double shift "search everywhere" box.

Switched maven URL to use "google()" instead, this works for all Android
Studio 3.0+, which covers all of stable/beta/canary.

Add specific AndroidManifest.xml to be used for the _all pseudo gradle
module since Android Studio now requires minSdk to not be specified in
the AndroidManifest.xml file.

Bug: 841529,827294,840368
Change-Id: Ifdee12bf7f9e7faf81cabf92dbf4c5613eb89996
Reviewed-on: https://chromium-review.googlesource.com/1053117Reviewed-by: Eric Stevenson <estevenson@chromium.org>
Reviewed-by: agrieve <agrieve@chromium.org>
Commit-Queue: Peter Wen <wnwen@chromium.org>
Cr-Commit-Position: refs/heads/master@{#557543}

build/android/gradle/AndroidManifest.xml

+<?xml version="1.0" encoding="utf-8"?>
+<!--
+  Copyright 2018 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 is a dummy manifest which is required by Android Studio's _all target.
+  No <uses-sdk> is allowed due to https://crbug.com/841529.
+-->
+<manifest xmlns:android="http://schemas.android.com/apk/res/android"
+    package="org.dummy">
+</manifest>

build/android/gradle/android.jinja

@@ -78,6 +78,14 @@ android {
 {% endif %}
     }
 
+{% if native is defined %}
+    externalNativeBuild {
+        cmake {
+            path "CMakeLists.txt"
+        }
+    }
+{% endif %}
+
     defaultConfig {
         vectorDrawables.useSupportLibrary = true
     }

build/android/gradle/cmake.jinja

+{# Copyright 2018 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. #}
+# Generated by //build/android/generate_gradle.py
+
+cmake_minimum_required(VERSION 3.4.1)
+
+project(chrome C CXX)
+
+{% for name, target in native.targets.iteritems() %}
+{% if target.sources is defined %}
+add_library("{{ name }}"
+{% for path in target.sources %}
+    {{ path }}
+{% endfor %}
+)
+{% endif %}
+{% endfor %}
+
+{% if native.includes is defined %}
+include_directories(
+{% for path in native.includes %}
+    {{ path }}
+{% endfor %}
+)
+{% endif %}

build/android/gradle/generate_gradle.py

@@ -9,6 +9,7 @@ import argparse
 import codecs
 import collections
 import glob
+import json
 import logging
 import os
 import re
@@ -32,13 +33,15 @@ sys.path.append(os.path.join(host_paths.DIR_SOURCE_ROOT, 'build'))
 import find_depot_tools  # pylint: disable=import-error
 
 _DEFAULT_ANDROID_MANIFEST_PATH = os.path.join(
-    host_paths.DIR_SOURCE_ROOT, 'build', 'android', 'AndroidManifest.xml')
+    host_paths.DIR_SOURCE_ROOT, 'build', 'android', 'gradle',
+    'AndroidManifest.xml')
 _FILE_DIR = os.path.dirname(__file__)
 _SRCJARS_SUBDIR = 'extracted-srcjars'
 _JNI_LIBS_SUBDIR = 'symlinked-libs'
 _ARMEABI_SUBDIR = 'armeabi'
 _RES_SUBDIR = 'extracted-res'
 _GRADLE_BUILD_FILE = 'build.gradle'
+_CMAKE_FILE = 'CMakeLists.txt'
 # This needs to come first alphabetically among all modules.
 _MODULE_ALL = '_all'
 _SRC_INTERNAL = os.path.join(
@@ -110,6 +113,17 @@ def _ReadPropertiesFile(path):
     return dict(l.rstrip().split('=', 1) for l in f if '=' in l)
 
 
+def _RunGnGen(output_dir, args):
+  cmd = [
+    os.path.join(find_depot_tools.DEPOT_TOOLS_PATH, 'gn'),
+    'gen',
+    output_dir,
+  ]
+  cmd.extend(args)
+  logging.info('Running: %r', cmd)
+  subprocess.check_call(cmd)
+
+
 def _RunNinja(output_dir, args, j):
   cmd = [
     os.path.join(find_depot_tools.DEPOT_TOOLS_PATH, 'ninja'),
@@ -596,8 +610,38 @@ def _IsTestDir(path):
           'testing/' in path)
 
 
-def _GenerateModuleAll(gradle_output_dir, generator, build_vars,
-    source_properties, jinja_processor):
+# Example: //chrome/android:monochrome
+def _GetNative(relative_func, target_names):
+  out_dir = constants.GetOutDirectory()
+  with open(os.path.join(out_dir, 'project.json'), 'r') as project_file:
+    projects = json.load(project_file)
+  project_targets = projects['targets']
+  root_dir = projects['build_settings']['root_path']
+  targets = {}
+  includes = set()
+  def process_paths(paths):
+    # Ignores leading //
+    return relative_func(
+        sorted(os.path.join(root_dir, path[2:]) for path in paths))
+  for target_name in target_names:
+    target = project_targets[target_name]
+    includes.update(target.get('include_dirs', []))
+    sources = target.get('sources', [])
+    if sources:
+      # CMake does not like forward slashes or colons for the target name.
+      filtered_name = target_name.replace('/', '.').replace(':', '-')
+      targets[filtered_name] = {
+          'sources': process_paths(sources),
+      }
+  return {
+      'targets': targets,
+      'includes': process_paths(includes),
+  }
+
+
+def _GenerateModuleAll(
+    gradle_output_dir, generator, build_vars, source_properties,
+    jinja_processor, native_targets):
   """Returns the data for a pseudo build.gradle of all dirs.
 
   See //docs/android_studio.md for more details."""
@@ -623,10 +667,17 @@ def _GenerateModuleAll(gradle_output_dir, generator, build_vars,
       'java_dirs': Relativize(test_java_dirs),
       'java_excludes': ['**/*.java'],
   }]
+  if native_targets:
+    variables['native'] = _GetNative(
+        relative_func=Relativize, target_names=native_targets)
   data = jinja_processor.Render(
       _TemplatePath(target_type.split('_')[0]), variables)
   _WriteFile(
       os.path.join(gradle_output_dir, _MODULE_ALL, _GRADLE_BUILD_FILE), data)
+  if native_targets:
+    cmake_data = jinja_processor.Render(_TemplatePath('cmake'), variables)
+    _WriteFile(
+        os.path.join(gradle_output_dir, _MODULE_ALL, _CMAKE_FILE), cmake_data)
 
 
 def _GenerateRootGradle(jinja_processor, channel):
@@ -752,6 +803,11 @@ def main():
   parser.add_argument('-j',
                       default=1000 if os.path.exists(_SRC_INTERNAL) else 50,
                       help='Value for number of parallel jobs for ninja')
+  parser.add_argument('--native-target',
+                      dest='native_targets',
+                      action='append',
+                      help='GN native targets to generate for. May be '
+                           'repeated.')
   version_group = parser.add_mutually_exclusive_group()
   version_group.add_argument('--beta',
                       action='store_true',
@@ -805,11 +861,15 @@ def main():
     targets_from_args.update(args.extra_targets)
 
   if args.all:
-    # Run GN gen if necessary (faster than running "gn gen" in the no-op case).
-    _RunNinja(constants.GetOutDirectory(), ['build.ninja'], args.j)
+    if args.native_targets:
+      _RunGnGen(output_dir, ['--ide=json'])
+    else:
+      # Faster than running "gn gen" in the no-op case.
+      _RunNinja(constants.GetOutDirectory(), ['build.ninja'], args.j)
     # Query ninja for all __build_config targets.
     targets = _QueryForAllGnTargets(output_dir)
   else:
+    assert not args.native_targets, 'Native editing requires --all.'
     targets = [re.sub(r'_test_apk$', '_test_apk__apk', t)
                for t in targets_from_args]
 
@@ -866,7 +926,7 @@ def main():
     project_entries.append((_MODULE_ALL, _MODULE_ALL))
     _GenerateModuleAll(
         _gradle_output_dir, generator, build_vars, source_properties,
-        jinja_processor)
+        jinja_processor, args.native_targets)
 
   _WriteFile(os.path.join(generator.project_dir, _GRADLE_BUILD_FILE),
              _GenerateRootGradle(jinja_processor, channel))

build/android/gradle/root.jinja

@@ -5,14 +5,12 @@
 
 buildscript {
     repositories {
+        google()
         jcenter()
-        maven {
-            url 'https://maven.google.com'
-        }
     }
     dependencies {
 {% if channel == 'canary' %}
-        classpath "com.android.tools.build:gradle:3.2.0-alpha04"
+        classpath "com.android.tools.build:gradle:3.2.0-alpha14"
 {% elif channel == 'beta' %}
         classpath "com.android.tools.build:gradle:3.1.0-beta4"
 {% else %}