Fix Javadoc generation + Javadoc

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=190916130

javadoc_combined.gradle

@@ -11,6 +11,8 @@
 // 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.
+apply from: "${rootDir}/javadoc_util.gradle"
+
 class CombinedJavadocPlugin implements Plugin<Project> {
 
   static final String TASK_NAME = "generateCombinedJavadoc"
@@ -20,29 +22,35 @@ class CombinedJavadocPlugin implements Plugin<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)
+          classpath = project.files([])
           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"
+            links "https://docs.oracle.com/javase/7/docs/api/",
+                "https://developer.android.com/reference"
             encoding = "UTF-8"
           }
           exclude "**/BuildConfig.java"
           exclude "**/R.java"
-          doLast {
+          doFirst {
             libraryModules.each { libraryModule ->
-              project.copy {
-                from "${libraryModule.projectDir}/src/main/javadoc"
-                into "${project.buildDir}/docs/javadoc"
+              libraryModule.android.libraryVariants.all { variant ->
+                def name = variant.buildType.name
+                if (name.equals("release")) {
+                  classpath +=
+                      libraryModule.project.files(
+                          variant.javaCompile.classpath.files,
+                          libraryModule.project.android.getBootClasspath())
+                }
               }
             }
           }
+          doLast {
+            project.javadocFixLinks()
+          }
         }
       }
     }
@@ -56,12 +64,6 @@ class CombinedJavadocPlugin implements Plugin<Project> {
     }
   }
 
-  // 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

@@ -11,6 +11,8 @@
 // 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.
+apply from: "${rootDir}/javadoc_util.gradle"
+
 android.libraryVariants.all { variant ->
     def name = variant.buildType.name
     if (!name.equals("release")) {
@@ -23,7 +25,7 @@ android.libraryVariants.all { variant ->
         options {
             links "http://docs.oracle.com/javase/7/docs/api/"
             linksOffline "https://developer.android.com/reference",
-                         "${android.sdkDirectory}/docs/reference"
+                "${android.sdkDirectory}/docs/reference"
             encoding = "UTF-8"
         }
         exclude "**/BuildConfig.java"
@@ -35,10 +37,7 @@ android.libraryVariants.all { variant ->
                     project.android.getBootClasspath())
         }
         doLast {
-            copy {
-                from "src/main/javadoc"
-                into "$buildDir/docs/javadoc"
-            }
+            project.javadocFixLinks()
         }
     }
 }

javadoc_util.gradle

@@ -0,0 +1,31 @@
+// Copyright (C) 2018 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.
+ext.javadocFixLinks = {
+  // Fix external Android links to target the top frame.
+  def androidRoot = "https://developer.android.com/reference/"
+  def androidLink = "<a href=\"(${androidRoot}.*?)\\?is-external=true\""
+  def androidFixed = "<a href=\"\\1\" target=\"_top\""
+  ant.replaceregexp(
+      match:androidLink, replace:androidFixed, flags:'g', byline:true) {
+    fileset(dir: "${project.buildDir}/docs/javadoc")
+  }
+  // Fix external Oracle links to use frames and target the top frame.
+  def oracleRoot = "https://docs.oracle.com/javase/7/docs/api/"
+  def oracleLink = "<a href=\"(${oracleRoot})(.*?)\\?is-external=true\""
+  def oracleFixed = "<a href=\"\\1/index.html\\?\\2\" target=\"_top\""
+  ant.replaceregexp(
+      match:oracleLink, replace:oracleFixed, flags:'g', byline:true) {
+    fileset(dir: "${project.buildDir}/docs/javadoc")
+  }
+}