Removes unused function in PepperGraphics2dHost

AFAICT it's not used

BUG=none
TEST=none

Change-Id: I170fc14bdb064524cecb8f90c17b35fac3f7f2b5
Reviewed-on: https://chromium-review.googlesource.com/728867Reviewed-by: Bill Budge <bbudge@chromium.org>
Commit-Queue: Scott Violet <sky@chromium.org>
Cr-Commit-Position: refs/heads/master@{#510228}

content/renderer/pepper/pepper_graphics_2d_host.cc

@@ -381,10 +381,6 @@ float PepperGraphics2DHost::GetScale() const { return scale_; }
 
 bool PepperGraphics2DHost::IsAlwaysOpaque() const { return is_always_opaque_; }
 
-PPB_ImageData_Impl* PepperGraphics2DHost::ImageData() {
-  return image_data_.get();
-}
-
 gfx::Size PepperGraphics2DHost::Size() const {
   if (!image_data_.get())
     return gfx::Size();

content/renderer/pepper/pepper_graphics_2d_host.h

@@ -84,7 +84,6 @@ class CONTENT_EXPORT PepperGraphics2DHost
   float GetScale() const;
   void SetLayerTransform(float scale, const PP_Point& transform);
   bool IsAlwaysOpaque() const;
-  PPB_ImageData_Impl* ImageData();
   gfx::Size Size() const;
 
   void ClearCache();