Generate combined Javadoc

Notes:
- Now only generating a single module Javadoc task for the
  release variant.
- Combined Javadoc now includes extensions. VP9 is excluded
  for now since it's failing for an unknown reason.

Issue: #2139

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=150865589

build.gradle

@@ -47,3 +47,5 @@ def getBintrayRepo() {
         property('publicRepo').toBoolean()
     return publicRepo ? 'exoplayer' : 'exoplayer-test'
 }
+
+apply from: 'javadoc_combined.gradle'

extensions/cronet/build.gradle

@@ -43,4 +43,4 @@ dependencies {
 ext {
     javadocTitle = 'Cronet extension'
 }
-apply from: '../../library_javadoc.gradle'
+apply from: '../../javadoc_library.gradle'

extensions/ffmpeg/build.gradle

@@ -36,4 +36,4 @@ dependencies {
 ext {
     javadocTitle = 'FFmpeg extension'
 }
-apply from: '../../library_javadoc.gradle'
+apply from: '../../javadoc_library.gradle'

extensions/flac/build.gradle

@@ -37,4 +37,4 @@ dependencies {
 ext {
     javadocTitle = 'FLAC extension'
 }
-apply from: '../../library_javadoc.gradle'
+apply from: '../../javadoc_library.gradle'

extensions/gvr/build.gradle

@@ -31,7 +31,7 @@ dependencies {
 ext {
     javadocTitle = 'GVR extension'
 }
-apply from: '../../library_javadoc.gradle'
+apply from: '../../javadoc_library.gradle'
 
 ext {
     releaseArtifact = 'extension-gvr'

extensions/okhttp/build.gradle

@@ -38,7 +38,7 @@ dependencies {
 ext {
     javadocTitle = 'OkHttp extension'
 }
-apply from: '../../library_javadoc.gradle'
+apply from: '../../javadoc_library.gradle'
 
 ext {
     releaseArtifact = 'extension-okhttp'

extensions/opus/build.gradle

@@ -36,4 +36,4 @@ dependencies {
 ext {
     javadocTitle = 'Opus extension'
 }
-apply from: '../../library_javadoc.gradle'
+apply from: '../../javadoc_library.gradle'

extensions/vp9/build.gradle

@@ -36,4 +36,4 @@ dependencies {
 ext {
     javadocTitle = 'VP9 extension'
 }
-apply from: '../../library_javadoc.gradle'
+apply from: '../../javadoc_library.gradle'

javadoc_combined.gradle

@@ -0,0 +1,68 @@
+// Copyright (C) 2017 The Android Open Source Project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+class CombinedJavadocPlugin implements Plugin<Project> {
+
+  static final String TASK_NAME = "generateCombinedJavadoc"
+
+  @Override
+  void apply(Project project) {
+    project.gradle.projectsEvaluated {
+      Set<Project> libraryModules = getLibraryModules(project)
+      if (!libraryModules.isEmpty()) {
+        String sdkDirectory = getSdkDirectory(libraryModules)
+        project.task(TASK_NAME, type: Javadoc) {
+          description = "Generates combined Javadoc."
+          title = "ExoPlayer library"
+          source = libraryModules.generateJavadoc.source
+          classpath = project.files(libraryModules.generateJavadoc.classpath)
+          destinationDir = project.file("$project.buildDir/docs/javadoc")
+          options {
+            links "http://docs.oracle.com/javase/7/docs/api/"
+            linksOffline "https://developer.android.com/reference",
+                         "${sdkDirectory}/docs/reference"
+            encoding = "UTF-8"
+          }
+          exclude "**/BuildConfig.java"
+          exclude "**/R.java"
+          destinationDir project.file("$project.buildDir/docs/javadoc")
+          doLast {
+            libraryModules.each { libraryModule ->
+              project.copy {
+                from "${libraryModule.projectDir}/src/main/javadoc"
+                into "${project.buildDir}/docs/javadoc"
+              }
+            }
+          }
+        }
+      }
+    }
+  }
+
+  // Returns Android library modules that declare a generateJavadoc task.
+  private Set<Project> getLibraryModules(Project project) {
+    project.subprojects.findAll {
+      it.plugins.findPlugin("com.android.library") &&
+      it.tasks.findByName("generateJavadoc")
+    }
+  }
+
+  // Returns the Android SDK directory given a set of Android library modules.
+  private String getSdkDirectory(Set<Project> libraryModules) {
+    // We can retrieve the Android SDK directory from any module.
+    return libraryModules.iterator().next().android.sdkDirectory
+  }
+
+}
+
+apply plugin: CombinedJavadocPlugin

javadoc_library.gradle

@@ -12,18 +12,24 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 android.libraryVariants.all { variant ->
-    task("generate${variant.name.capitalize()}Javadoc", type: Javadoc) {
-        description "Generates Javadoc for $variant.name."
-        title = javadocTitle
+    def name = variant.buildType.name
+    if (!name.equals("release")) {
+        return; // Skip non-release builds.
+    }
+    task("generateJavadoc", type: Javadoc) {
+        description = "Generates Javadoc for the ${javadocTitle}."
+        title = "ExoPlayer ${javadocTitle}"
         source = variant.javaCompile.source
-        classpath = files(variant.javaCompile.classpath.files, project.android.getBootClasspath())
+        classpath = files(variant.javaCompile.classpath.files,
+	                  project.android.getBootClasspath())
         options {
             links "http://docs.oracle.com/javase/7/docs/api/"
-            linksOffline "https://developer.android.com/reference","${android.sdkDirectory}/docs/reference"
-            encoding = 'UTF-8'
+            linksOffline "https://developer.android.com/reference",
+                         "${android.sdkDirectory}/docs/reference"
+            encoding = "UTF-8"
         }
-        exclude '**/BuildConfig.java'
-        exclude '**/R.java'
+        exclude "**/BuildConfig.java"
+        exclude "**/R.java"
         doLast {
             copy {
                 from "src/main/javadoc"

library/core/build.gradle

@@ -46,9 +46,9 @@ dependencies {
 }
 
 ext {
-    javadocTitle = 'Core'
+    javadocTitle = 'Core module'
 }
-apply from: '../../library_javadoc.gradle'
+apply from: '../../javadoc_library.gradle'
 
 ext {
     releaseArtifact = 'exoplayer-core'

library/dash/build.gradle

@@ -38,9 +38,9 @@ dependencies {
 }
 
 ext {
-    javadocTitle = 'DASH'
+    javadocTitle = 'DASH module'
 }
-apply from: '../../library_javadoc.gradle'
+apply from: '../../javadoc_library.gradle'
 
 ext {
     releaseArtifact = 'exoplayer-dash'

library/hls/build.gradle

@@ -32,9 +32,9 @@ dependencies {
 }
 
 ext {
-    javadocTitle = 'HLS'
+    javadocTitle = 'HLS module'
 }
-apply from: '../../library_javadoc.gradle'
+apply from: '../../javadoc_library.gradle'
 
 ext {
     releaseArtifact = 'exoplayer-hls'

library/smoothstreaming/build.gradle

@@ -38,9 +38,9 @@ dependencies {
 }
 
 ext {
-    javadocTitle = 'SmoothStreaming'
+    javadocTitle = 'SmoothStreaming module'
 }
-apply from: '../../library_javadoc.gradle'
+apply from: '../../javadoc_library.gradle'
 
 ext {
     releaseArtifact = 'exoplayer-smoothstreaming'

library/ui/build.gradle

@@ -29,9 +29,9 @@ dependencies {
 }
 
 ext {
-    javadocTitle = 'UI'
+    javadocTitle = 'UI module'
 }
-apply from: '../../library_javadoc.gradle'
+apply from: '../../javadoc_library.gradle'
 
 ext {
     releaseArtifact = 'exoplayer-ui'