Revert 96327 - Switch over to using SkRegions to calculate dirty areas.

remoting/host/differ.h

Index: remoting/host/differ.h
===================================================================
--- remoting/host/differ.h	(revision 96327)
+++ remoting/host/differ.h	(working copy)
@@ -9,16 +9,13 @@
 
 #include "base/basictypes.h"
 #include "base/memory/scoped_ptr.h"
-#include "third_party/skia/include/core/SkRegion.h"
+#include "remoting/base/types.h"
+#include "ui/gfx/rect.h"
 
 namespace remoting {
 
 typedef uint8 DiffInfo;
 
-// TODO: Simplify differ now that we are working with SkRegions.
-// diff_info_ should no longer be needed, as we can put our data directly into
-// the region that we are calculating.
-// http://crbug.com/92379
 class Differ {
  public:
   // Create a differ that operates on bitmaps with the specified width, height
@@ -31,23 +28,25 @@
   int bytes_per_pixel() { return bytes_per_pixel_; }
   int bytes_per_row() { return bytes_per_row_; }
 
-  // Given the previous and current screen buffer, calculate the dirty region
-  // that encloses all of the changed pixels in the new screen.
-  void CalcDirtyRegion(const void* prev_buffer, const void* curr_buffer,
-                       SkRegion* region);
+  // Given the previous and current screen buffer, calculate the set of
+  // rectangles that enclose all the changed pixels in the new screen.
+  void CalcDirtyRects(const void* prev_buffer, const void* curr_buffer,
+                      InvalidRects* rects);
 
- private:
-  // Allow tests to access our private parts.
-  friend class DifferTest;
-
   // Identify all of the blocks that contain changed pixels.
   void MarkDirtyBlocks(const void* prev_buffer, const void* curr_buffer);
 
   // After the dirty blocks have been identified, this routine merges adjacent
-  // blocks into a region.
-  // The goal is to minimize the region that covers the dirty blocks.
-  void MergeBlocks(SkRegion* region);
+  // blocks into larger rectangular units.
+  // The goal is to minimize the number of rects that cover the dirty blocks,
+  // although it is not required to calc the absolute minimum of rects.
+  void MergeBlocks(InvalidRects* rects);
 
+  // Allow tests to access our private parts.
+  friend class DifferTest;
+
+ private:
+
   // Check for diffs in upper-left portion of the block. The size of the portion
   // to check is specified by the |width| and |height| values.
   // Note that if we force the capturer to always return images whose width and