gpu: Add the ability to wait on upload completion.

ui/gl/async_pixel_transfer_delegate_android.cc

Index: ui/gl/async_pixel_transfer_delegate_android.cc
diff --git a/ui/gl/async_pixel_transfer_delegate_android.cc b/ui/gl/async_pixel_transfer_delegate_android.cc
index a594c9468e341848f22f4bd2c7a1c5326d2a7247..7e603ba4ebaaf8a96fd9fdded4c38c6b0fb82b7d 100644
--- a/ui/gl/async_pixel_transfer_delegate_android.cc
+++ b/ui/gl/async_pixel_transfer_delegate_android.cc
@@ -13,6 +13,7 @@
 #include "base/memory/ref_counted.h"
 #include "base/process_util.h"
 #include "base/shared_memory.h"
+#include "base/synchronization/waitable_event.h"
 #include "base/threading/thread.h"
 #include "build/build_config.h"
 #include "ui/gl/async_pixel_transfer_delegate.h"
@@ -198,6 +199,9 @@ SafeSharedMemoryPool* safe_shared_memory_pool() {
   return g_transfer_thread.Pointer()->safe_shared_memory_pool();
 }
 
+void SignalCompletion(base::WaitableEvent* completion) {
+  completion->Signal();
+}
 
 } // namespace
 
@@ -380,6 +384,7 @@ class AsyncPixelTransferDelegateAndroid
   virtual void AsyncNotifyCompletion(
       const AsyncMemoryParams& mem_params,
       const CompletionCallback& callback) OVERRIDE;
+  virtual void WaitOnUploadCompletion() OVERRIDE;
   virtual void AsyncTexImage2D(
       AsyncPixelTransferState* state,
       const AsyncTexImage2DParams& tex_params,
@@ -504,6 +509,26 @@ void AsyncPixelTransferDelegateAndroid::AsyncNotifyCompletion(
                  callback));
 }
 
+void AsyncPixelTransferDelegateAndroid::WaitOnUploadCompletion() {
+  // TODO(epenner): Move thread priorities to base. (crbug.com/170549)
+  int default_nice_value = 0;  // Default priority.
+  int idle_nice_value    = 10; // Idle priority.
+  setpriority(PRIO_PROCESS,
+              g_transfer_thread.Pointer()->thread_id(),
+              default_nice_value);
+
+  base::WaitableEvent completion(true, false);
+  transfer_message_loop_proxy()->PostTask(
+      FROM_HERE,
+      base::Bind(&SignalCompletion, &completion));
+  completion.Wait();
+
+  // TODO(epenner): Move thread priorities to base. (crbug.com/170549)
+  setpriority(PRIO_PROCESS,
+              g_transfer_thread.Pointer()->thread_id(),
+              idle_nice_value);
+}
+
 void AsyncPixelTransferDelegateAndroid::AsyncTexImage2D(
     AsyncPixelTransferState* transfer_state,
     const AsyncTexImage2DParams& tex_params,