ui: Eliminate allocating gfx::Canvas on the heap for every view.

ui/gfx/render_text_unittest.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "ui/gfx/render_text.h"
 
 #include <algorithm>
 
 #include "base/format_macros.h"
 #include "base/i18n/break_iterator.h"
@@ skipping 2780 matching lines @@
       L"gAXAXAXAXAXAXA",
       // TODO(dschuyler): A-Ring draws outside GetStringSize; crbug.com/459812.
       // L"g\x00C5X\x00C5X\x00C5X\x00C5X\x00C5X\x00C5X\x00C5",
       L"\x0647\x0654\x0647\x0654\x0647\x0654\x0647\x0654\x0645\x0631\x062D"
       L"\x0628\x0627"};
   const Size kCanvasSize(300, 50);
   const int kTestSize = 10;
 
   skia::RefPtr<SkSurface> surface = skia::AdoptRef(
       SkSurface::NewRasterN32Premul(kCanvasSize.width(), kCanvasSize.height()));
-  scoped_ptr<Canvas> canvas(
-      Canvas::CreateCanvasWithoutScaling(surface->getCanvas(), 1.0f));
+  Canvas canvas(surface->getCanvas(), 1.0f);
   scoped_ptr<RenderText> render_text(RenderText::CreateInstance());
   render_text->SetHorizontalAlignment(ALIGN_LEFT);
   render_text->SetColor(SK_ColorBLACK);
 
   for (auto string : kTestStrings) {
     surface->getCanvas()->clear(SK_ColorWHITE);
     render_text->SetText(WideToUTF16(string));
     const Size string_size = render_text->GetStringSize();
     render_text->ApplyBaselineStyle(SUPERSCRIPT, Range(1, 2));
     render_text->ApplyBaselineStyle(SUPERIOR, Range(3, 4));
     render_text->ApplyBaselineStyle(INFERIOR, Range(5, 6));
     render_text->ApplyBaselineStyle(SUBSCRIPT, Range(7, 8));
     render_text->SetStyle(BOLD, true);
     render_text->SetDisplayRect(
         Rect(kTestSize, kTestSize, string_size.width(), string_size.height()));
     // Allow the RenderText to paint outside of its display rect.
     render_text->set_clip_to_display_rect(false);
     ASSERT_LE(string_size.width() + kTestSize * 2, kCanvasSize.width());
 
-    render_text->Draw(canvas.get());
+    render_text->Draw(&canvas);
     ASSERT_LT(string_size.width() + kTestSize, kCanvasSize.width());
     const uint32* buffer =
         static_cast<const uint32*>(surface->peekPixels(nullptr, nullptr));
     ASSERT_NE(nullptr, buffer);
     TestRectangleBuffer rect_buffer(string, buffer, kCanvasSize.width(),
                                     kCanvasSize.height());
     {
 #if !defined(OS_CHROMEOS)
       // TODO(dschuyler): On ChromeOS text draws above the GetStringSize rect.
       SCOPED_TRACE("TextDoesntClip Top Side");
@@ skipping 41 matching lines @@
 
 // Ensure that the text will clip to the display rect. Draws to a canvas and
 // checks whether any pixel beyond the bounding rectangle is colored.
 TEST_F(RenderTextTest, TextDoesClip) {
   const wchar_t* kTestStrings[] = {L"TEST", L"W", L"WWWW", L"gAXAXWWWW"};
   const Size kCanvasSize(300, 50);
   const int kTestSize = 10;
 
   skia::RefPtr<SkSurface> surface = skia::AdoptRef(
       SkSurface::NewRasterN32Premul(kCanvasSize.width(), kCanvasSize.height()));
-  scoped_ptr<Canvas> canvas(
-      Canvas::CreateCanvasWithoutScaling(surface->getCanvas(), 1.0f));
+  Canvas > canvas(surface->getCanvas(), 1.0f);
   scoped_ptr<RenderText> render_text(RenderText::CreateInstance());
   render_text->SetHorizontalAlignment(ALIGN_LEFT);
   render_text->SetColor(SK_ColorBLACK);
 
   for (auto string : kTestStrings) {
     surface->getCanvas()->clear(SK_ColorWHITE);
     render_text->SetText(WideToUTF16(string));
     const Size string_size = render_text->GetStringSize();
     int fake_width = string_size.width() / 2;
     int fake_height = string_size.height() / 2;
     render_text->SetDisplayRect(
         Rect(kTestSize, kTestSize, fake_width, fake_height));
     render_text->set_clip_to_display_rect(true);
-    render_text->Draw(canvas.get());
+    render_text->Draw(&canvas);
     ASSERT_LT(string_size.width() + kTestSize, kCanvasSize.width());
     const uint32* buffer =
         static_cast<const uint32*>(surface->peekPixels(nullptr, nullptr));
     ASSERT_NE(nullptr, buffer);
     TestRectangleBuffer rect_buffer(string, buffer, kCanvasSize.width(),
                                     kCanvasSize.height());
     {
       SCOPED_TRACE("TextDoesClip Top Side");
       rect_buffer.EnsureSolidRect(SK_ColorWHITE, 0, 0, kCanvasSize.width(),
                                   kTestSize);
@@ skipping 33 matching lines @@
   string_size.set_width(string_size.width() / 2);
   render_text.SetDisplayRect(gfx::Rect(string_size));
   render_text.EnsureLayout();
   CFIndex glyph_count = CTLineGetGlyphCount(render_text.line_);
   EXPECT_GT(text.size(), static_cast<size_t>(glyph_count));
   EXPECT_NE(0, glyph_count);
 }
 #endif
 
 }  // namespace gfx