Remove additional FlushSkia in CanvasResourceProvider::WritePixels

This effectively reverts:

https://chromium-review.googlesource.com/c/chromium/src/+/1561611 (Explicitly flush after an SkCanvas::writePixels)

Together with the following Skia-side CL, this patch fixes Chrome's flushing behavior for platforms that prefer flushes over VRAM use (i.e., ANGLE) and for platforms that don't (e.g., Android).

https://skia-review.googlesource.com/c/skia/+/210062 (Change flushing policy in GrContextPriv::writeSurfacePixels)

Here are the perf numbers on Android and Windows for the putImageData performance test:

                              Android (Nexus 5x)   Windows (i.e., ANGLE)
Current Chrome                        112.9             512.1
Chrome w/ this CL                     131.9             334.8
Chrome w/ this CL and 210062          133.6             589.4

So, after both CLs have landed, Android will be faster while Windows will, roughly, remain the same.

Bug: 942538, 953720
Change-Id: I5db9f9fbc158e2132b1c532c40b60277a87d5e83
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1582181Reviewed-by: Florin Malita <fmalita@chromium.org>
Commit-Queue: Robert Phillips <robertphillips@google.com>
Cr-Commit-Position: refs/heads/master@{#653657}

third_party/blink/renderer/platform/graphics/canvas_resource_provider.cc

@@ -1083,13 +1083,8 @@ bool CanvasResourceProvider::WritePixels(const SkImageInfo& orig_info,
   TRACE_EVENT0("blink", "CanvasResourceProvider::WritePixels");
 
   DCHECK(IsValid());
-  if (GetSkSurface()->getCanvas()->writePixels(orig_info, pixels, row_bytes, x,
-                                               y)) {
-    FlushSkia();
-    return true;
-  }
-
-  return false;
+  return GetSkSurface()->getCanvas()->writePixels(orig_info, pixels, row_bytes,
+                                                  x, y);
 }
 
 void CanvasResourceProvider::Clear() {