Prepare SyntheticPointerAction to handle touch actions for multiple fingers

content/browser/renderer_host/input/synthetic_pointer.h

Index: content/browser/renderer_host/input/synthetic_pointer.h
diff --git a/content/browser/renderer_host/input/synthetic_pointer.h b/content/browser/renderer_host/input/synthetic_pointer.h
index b102a075a9333051a498d4a02bd756fc33d57915..faa73b3bf5e1634a6923d61fe4dbdd4150a9b5a8 100644
--- a/content/browser/renderer_host/input/synthetic_pointer.h
+++ b/content/browser/renderer_host/input/synthetic_pointer.h
@@ -40,6 +40,9 @@ class CONTENT_EXPORT SyntheticPointer {
                        SyntheticGestureTarget* target,
                        const base::TimeTicks& timestamp) = 0;
 
+  virtual SyntheticGestureParams::GestureSourceType PointerSourceType()

[tdresser, 2016/07/08 12:22:14]

We could just call this "SourceType", or even "Source".

The fact that we're referring to the pointer is implicit, since it's in the
SyntheticPointer class.

[lanwei, 2016/07/13 02:23:55]

Done.

+      const = 0;
+
  protected:
   static double ConvertTimestampToSeconds(const base::TimeTicks& timestamp);