mac: Add support for asynchronous dictionary lookup

content/browser/renderer_host/text_input_client_mac.h

Index: content/browser/renderer_host/text_input_client_mac.h
diff --git a/content/browser/renderer_host/text_input_client_mac.h b/content/browser/renderer_host/text_input_client_mac.h
index 53318f95cb5bb49efe6403fe3bb62a05cbce2538..2c54fce54cd0d0440c7bebe2361dc4596f234302 100644
--- a/content/browser/renderer_host/text_input_client_mac.h
+++ b/content/browser/renderer_host/text_input_client_mac.h
@@ -7,6 +7,7 @@
 
 #import <Cocoa/Cocoa.h>
 
+#include "base/mac/scoped_block.h"
 #include "base/mac/scoped_nsobject.h"
 #include "base/synchronization/condition_variable.h"
 #include "base/synchronization/lock.h"
@@ -37,6 +38,11 @@ class CONTENT_EXPORT TextInputClientMac {
   // Returns the singleton instance.
   static TextInputClientMac* GetInstance();
 
+  void GetStringAtPoint(RenderWidgetHost* rwh,
+                        gfx::Point point,
+                        void (^replyHandler)(NSAttributedString*, NSPoint));

[Avi (use Gerrit), 2014/03/12 04:55:40]

Two questions:

1. Is this async, given the callback? If so, then fix the class comment above
about how all these methods are synchronous.

2. What are the thread guarantees here about the reply handler? This function
needs to be called on the UI thread, of course, but you should document what
thread guarantees are given for the callback.

[Andre, 2014/03/12 16:59:26]

1. Yes, this is async. Updated comments accordingly.
2. Reply callback happens on the IO thread. Added documentation.

+  void GetStringAtPointReply(NSAttributedString*, NSPoint);
+
   // Each of the three methods mentioned above has an associated pair of methods
   // to get data from the renderer. The Get*() methods block the calling thread
   // (always the UI thread) with a short timeout after the async message has
@@ -82,6 +88,8 @@ class CONTENT_EXPORT TextInputClientMac {
   base::Lock lock_;
   base::ConditionVariable condition_;
 
+  base::mac::ScopedBlock<void(^)(NSAttributedString*, NSPoint)> replyHandler_;
+
   DISALLOW_COPY_AND_ASSIGN(TextInputClientMac);
 };