android: Migrate old content readback to use async readback (and delegated renderer)

content/public/browser/android/content_view_core.h

Index: content/public/browser/android/content_view_core.h
diff --git a/content/public/browser/android/content_view_core.h b/content/public/browser/android/content_view_core.h
index 85766ee504c6ef347320cd6a4e5957b4280f78ea..493a1dc4f45410567578bf88577a8582ca44c572 100644
--- a/content/public/browser/android/content_view_core.h
+++ b/content/public/browser/android/content_view_core.h
@@ -12,6 +12,8 @@
 #include "content/common/content_export.h"
 #include "content/public/browser/navigation_controller.h"
 
+class SkBitmap;
+
 namespace cc {
 class Layer;
 }
@@ -48,9 +50,19 @@ class CONTENT_EXPORT ContentViewCore {
   virtual void LoadUrl(NavigationController::LoadURLParams& params) = 0;
   virtual jint GetCurrentRenderProcessId(JNIEnv* env, jobject obj) = 0;
   virtual void ShowPastePopup(int x, int y) = 0;
-  virtual unsigned int GetScaledContentTexture(
+
+  // Called with the result of a content readback.  The boolean parameter
+  // indicates whether the content reaback was successful or not.  If the
+  // readback was successful, an SkBitmap of the content is passed as the second
+  // parameter.
+  typedef base::Callback<void(bool, const SkBitmap&)> ContentBitmapCallback;

[aelias_OOO_until_Jul13, 2014/02/01 02:09:20]

Hmm, sorry for changing my mind, but it looks like this callback is a
pre-existing pattern in a lot of places.  I guess we should keep using
base::Callback<void(bool, const SkBitmap&)> for now and rename it in a future
cleanup patch.  I also think "PixelReadbackCallback" would be a better name.

[powei, 2014/02/03 10:06:52]

Done.

+
+  // Request a scaled content readback.  The result is passed through the
+  // callback.  |out_size| is returned with the size of the content.
+  virtual void GetScaledContentBitmap(
       float scale,
-      gfx::Size* out_size) = 0;
+      gfx::Size* out_size,
+      const ContentBitmapCallback& result_callback) = 0;
   virtual float GetDpiScale() const = 0;
   virtual void RequestContentClipping(const gfx::Rect& clipping,
                                       const gfx::Size& content_size) = 0;