Remove PlatformCanvas::GetBitmapContext()

This API is only used from ~CanvasSkiaPaint(), and is similar in behavior
to ScopedPlatformPaint::GetNativeDrawingContext().

Refactor the only client to use the latter, get rid of the GetBitmapContext()
virtual and platform_device_foo stubs.

BUG=675977
R=reed@google.com
TBR=danakj@chromium.org

Review-Url: https://codereview.chromium.org/2607603004
Cr-Commit-Position: refs/heads/master@{#441127}

skia/BUILD.gn

@@ -203,9 +203,6 @@ component("skia") {
     "ext/image_operations.cc",
     "ext/opacity_filter_canvas.cc",
     "ext/platform_device.cc",
-    "ext/platform_device_linux.cc",
-    "ext/platform_device_mac.cc",
-    "ext/platform_device_win.cc",
     "ext/recursive_gaussian_convolution.cc",
     "ext/skia_histogram.cc",
     "ext/skia_memory_dump_provider.cc",
@@ -420,7 +417,6 @@ component("skia") {
 
   if (is_android) {
     set_sources_assignment_filter([])
-    sources += [ "ext/platform_device_linux.cc" ]
     set_sources_assignment_filter(sources_assignment_filter)
     deps += [
       "//third_party/android_tools:cpu_features",

skia/ext/bitmap_platform_device_mac.cc

@@ -244,8 +244,9 @@ BitmapPlatformDevice::~BitmapPlatformDevice() {
     CGContextRelease(bitmap_context_);
 }
 
-CGContextRef BitmapPlatformDevice::GetBitmapContext(const SkMatrix& transform,
-                                                    const SkIRect& clip_bounds) {
+NativeDrawingContext BitmapPlatformDevice::BeginPlatformPaint(
+    const SkMatrix& transform,
+    const SkIRect& clip_bounds) {
   LoadConfig(transform, clip_bounds);
   return bitmap_context_;
 }

skia/ext/bitmap_platform_device_mac.h

@@ -46,17 +46,16 @@ class SK_API BitmapPlatformDevice : public SkBitmapDevice, public PlatformDevice
 
   ~BitmapPlatformDevice() override;
 
-  // PlatformDevice overrides
-  CGContextRef GetBitmapContext(const SkMatrix& transform,
-                                const SkIRect& clip_bounds) override;
-
  protected:
   BitmapPlatformDevice(CGContextRef context,
                        const SkBitmap& bitmap);
 
   SkBaseDevice* onCreateDevice(const CreateInfo&, const SkPaint*) override;
 
  private:
+  NativeDrawingContext BeginPlatformPaint(const SkMatrix& transform,
+                                          const SkIRect& clip_bounds) override;
+
   void ReleaseBitmapContext();
 
   // Loads the current transform and clip into the context. Can be called even

skia/ext/platform_canvas.cc

@@ -88,18 +88,6 @@ void SetIsPreviewMetafile(const SkCanvas& canvas, bool is_preview) {
 bool IsPreviewMetafile(const SkCanvas& canvas) {
   return GetBoolMetaData(canvas, kIsPreviewMetafileKey);
 }
-
-CGContextRef GetBitmapContext(const SkCanvas& canvas) {
-  PlatformDevice* platform_device =
-      GetPlatformDevice(canvas.getTopDevice(true));
-  SkIRect clip_bounds;
-  canvas.getClipDeviceBounds(&clip_bounds);
-  return platform_device ?
-      platform_device->GetBitmapContext(
-          canvas.getTotalMatrix(), clip_bounds) :
-      nullptr;
-}
-
 #endif
 
 ScopedPlatformPaint::ScopedPlatformPaint(SkCanvas* canvas) :

skia/ext/platform_canvas.h

@@ -154,10 +154,6 @@ SK_API SkMetaData& GetMetaData(const SkCanvas& canvas);
 #if defined(OS_MACOSX)
 SK_API void SetIsPreviewMetafile(const SkCanvas& canvas, bool is_preview);
 SK_API bool IsPreviewMetafile(const SkCanvas& canvas);
-
-// Returns the CGContext that backing the SkCanvas.
-// Returns NULL if none is bound.
-SK_API CGContextRef GetBitmapContext(const SkCanvas& canvas);
 #endif
 
 }  // namespace skia

skia/ext/platform_device.cc

@@ -31,4 +31,6 @@ PlatformDevice* GetPlatformDevice(SkBaseDevice* device) {
   return NULL;
 }
 
+PlatformDevice::~PlatformDevice() {}
+
 }  // namespace skia

skia/ext/platform_device.h

@@ -7,11 +7,6 @@
 
 #include "build/build_config.h"
 
-#if defined(OS_WIN)
-#include <windows.h>
-#include <vector>
-#endif
-
 #include "skia/ext/native_drawing_context.h"
 #include "third_party/skia/include/core/SkBitmapDevice.h"
 #include "third_party/skia/include/core/SkTypes.h"
@@ -50,22 +45,14 @@ SK_API PlatformDevice* GetPlatformDevice(SkBaseDevice* device);
 // from it.
 class SK_API PlatformDevice {
  public:
-  virtual ~PlatformDevice() {}
-
-#if defined(OS_MACOSX)
-  // The CGContext that corresponds to the bitmap, used for CoreGraphics
-  // operations drawing into the bitmap. This is possibly heavyweight, so it
-  // should exist only during one pass of rendering.
-  virtual CGContextRef GetBitmapContext(const SkMatrix& transform,
-                                        const SkIRect& clip_bounds) = 0;
-#endif
+  virtual ~PlatformDevice();
 
  private:
   // The DC that corresponds to the bitmap, used for GDI operations drawing
   // into the bitmap. This is possibly heavyweight, so it should be existant
   // only during one pass of rendering.
   virtual NativeDrawingContext BeginPlatformPaint(const SkMatrix& transform,
-                                                  const SkIRect& clip_bounds);
+                                                  const SkIRect& clip_bounds) = 0;
 
   friend class ScopedPlatformPaint;
 };

ui/gfx/canvas_paint_mac.mm

@@ -25,8 +25,9 @@
     canvas->restoreToCount(1);
 
     // Blit the dirty rect to the current context.
+    skia::ScopedPlatformPaint spp(canvas);
     CGImageRef image =
-        CGBitmapContextCreateImage(skia::GetBitmapContext(*canvas));
+        CGBitmapContextCreateImage(spp.GetNativeDrawingContext());
     CGRect dest_rect = NSRectToCGRect(rectangle_);
 
     CGContextRef destination_context =