Turn the utility process image decoder into a Mojo service.

chrome/browser/image_decoder.h

Index: chrome/browser/image_decoder.h
diff --git a/chrome/browser/image_decoder.h b/chrome/browser/image_decoder.h
index 9e0b3edeaff92cff17a04aac93b0cbc236e06c9e..09167604eee3184caf9e3b6e26bb4d86bb0105d5 100644
--- a/chrome/browser/image_decoder.h
+++ b/chrome/browser/image_decoder.h
@@ -11,6 +11,7 @@
 
 #include "base/lazy_instance.h"
 #include "base/memory/ref_counted.h"
+#include "base/memory/scoped_ptr.h"
 #include "base/sequence_checker.h"
 #include "base/sequenced_task_runner.h"
 #include "base/synchronization/lock.h"
@@ -20,6 +21,14 @@
 
 class SkBitmap;
 
+namespace image_decoder {
+class ImageDecoder;
+}
+
+namespace mojo {
+template <typename T> class InterfacePtr;
+}
+
 // This is a helper class for decoding images safely in a utility process. To
 // use this, call ImageDecoder::Start(...) or
 // ImageDecoder::StartWithOptions(...) on any thread.
@@ -152,6 +161,10 @@ class ImageDecoder : public content::UtilityProcessHostClient {
   // unless a new decoding request resets the timer.
   scoped_ptr<base::DelayTimer<ImageDecoder>> batch_mode_timer_;
 
+  // Mojo service connection. Must always be bound/reset and used on the IO
+  // thread.
+  scoped_ptr<mojo::InterfacePtr<image_decoder::ImageDecoder>> decoder_;
+
   DISALLOW_COPY_AND_ASSIGN(ImageDecoder);
 };