content: Implement dynamic priorities for raster threads.

base/threading/platform_thread_android.cc

Index: base/threading/platform_thread_android.cc
diff --git a/base/threading/platform_thread_android.cc b/base/threading/platform_thread_android.cc
index fd5e54d8af961fe03c90d3bd6c7b61b111aa6f13..a40c9cf39571cc00ed41b951b8f762d7d7a0f4af 100644
--- a/base/threading/platform_thread_android.cc
+++ b/base/threading/platform_thread_android.cc
@@ -51,14 +51,37 @@ bool GetCurrentThreadPriorityForPlatform(ThreadPriority* priority) {
   DCHECK(priority);
   *priority = ThreadPriority::NORMAL;
   JNIEnv* env = base::android::AttachCurrentThread();
-  if (Java_ThreadUtils_isThreadPriorityAudio(
-      env, PlatformThread::CurrentId())) {
+  if (Java_ThreadUtils_isThreadPriorityBackground(
+          env, PlatformThread::CurrentId())) {
+    *priority = ThreadPriority::BACKGROUND;
+    return true;
+  } else if (Java_ThreadUtils_isThreadPriorityNormal(
+                 env, PlatformThread::CurrentId())) {
+    *priority = ThreadPriority::NORMAL;
+    return true;
+  } else if (Java_ThreadUtils_isThreadPriorityAudio(
+                 env, PlatformThread::CurrentId())) {
     *priority = ThreadPriority::REALTIME_AUDIO;
     return true;
   }
   return false;
 }
 
+bool SetChildThreadPriorityInCurrentProcess(PlatformThreadId tid,
+                                            ThreadPriority priority) {
+  // On Android, we set the Normal or Background priority through JNI.
+  // Other priorities are not yet supported by current function.
+  JNIEnv* env = base::android::AttachCurrentThread();
+  if (priority == ThreadPriority::BACKGROUND) {
+    Java_ThreadUtils_setThreadPriorityBackground(env, tid);
+    return true;
+  } else if (priority == ThreadPriority::NORMAL) {
+    Java_ThreadUtils_setThreadPriorityNormal(env, tid);
+    return true;
+  }
+  return false;
+}
+
 }  // namespace internal
 
 void PlatformThread::SetName(const std::string& name) {