Remove origin field from GrSurface (take 2)

This mainly consists of rm origin from GrSurface and the wrapBackEnd*
methods and then re-adding an explicit origin parameter to all the
GrGpu methods that need it.

TBR=bsalomon@google.com

Change-Id: I4248b2a4749ef844da4233ce53b0dc504bc9eb74
Reviewed-on: https://skia-review.googlesource.com/30280
Commit-Queue: Robert Phillips <robertphillips@google.com>
Reviewed-by: Brian Salomon <bsalomon@google.com>
diff --git a/tests/TransferPixelsTest.cpp b/tests/TransferPixelsTest.cpp
index daeaada..722707a 100755
--- a/tests/TransferPixelsTest.cpp
+++ b/tests/TransferPixelsTest.cpp
@@ -109,7 +109,7 @@
     REPORTER_ASSERT(reporter, result);
 
     memset(dstBuffer.get(), 0xCDCD, size);
-    result = context->getGpu()->readPixels(tex.get(), 0, 0, kTextureWidth, kTextureHeight,
+    result = context->getGpu()->readPixels(tex.get(), origin, 0, 0, kTextureWidth, kTextureHeight,
                                            config, dstBuffer.get(), rowBytes);
     if (result) {
         REPORTER_ASSERT(reporter, does_full_buffer_contain_correct_values(srcBuffer,
@@ -141,7 +141,7 @@
     REPORTER_ASSERT(reporter, result);
 
     memset(dstBuffer.get(), 0xCDCD, size);
-    result = context->getGpu()->readPixels(tex.get(), 0, 0, kTextureWidth, kTextureHeight,
+    result = context->getGpu()->readPixels(tex.get(), origin, 0, 0, kTextureWidth, kTextureHeight,
                                            config, dstBuffer.get(), rowBytes);
     if (result) {
         REPORTER_ASSERT(reporter, does_full_buffer_contain_correct_values(srcBuffer,