Relanding this with font test fixes for gdi.

ui/gfx/platform_font_win.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/platform_font_win.h"
 
 #include <algorithm>
 #include <dwrite.h>
 #include <math.h>
 #include <windows.h>
@@ skipping 193 matching lines @@
   InitWithCopyOfHFONT(native_font);
 }
 
 PlatformFontWin::PlatformFontWin(const std::string& font_name,
                                  int font_size) {
   InitWithFontNameAndSize(font_name, font_size);
 }
 
 Font PlatformFontWin::DeriveFontWithHeight(int height, int style) {
   DCHECK_GE(height, 0);
-  if (GetHeight() == height && GetStyle() == style)
-    return Font(this);
 
-  // CreateFontIndirect() doesn't return the largest size for the given height
-  // when decreasing the height. Iterate to find it.
-  if (GetHeight() > height) {
-    const int min_font_size = GetMinimumFontSize();
-    Font font = DeriveFont(-1, style);
-    int font_height = font.GetHeight();
-    int font_size = font.GetFontSize();
-    while (font_height > height && font_size != min_font_size) {
-      font = font.Derive(-1, style);
-      if (font_height == font.GetHeight() && font_size == font.GetFontSize())
-        break;
-      font_height = font.GetHeight();
-      font_size = font.GetFontSize();
-    }
-    return font;
-  }
-
+  // Create a font with a height near that of the target height.
   LOGFONT font_info;
   GetObject(GetNativeFont(), sizeof(LOGFONT), &font_info);
   font_info.lfHeight = height;
   SetLogFontStyle(style, &font_info);
 
   HFONT hfont = CreateFontIndirect(&font_info);
-  return DeriveWithCorrectedSize(hfont);
+  Font font(new PlatformFontWin(CreateHFontRef(hfont)));
+
+  // Respect the minimum font size constraint.
+  const int min_font_size = GetMinimumFontSize();
+
+  // CreateFontIndirect() doesn't return the largest size for the given height
+  // when decreasing the height. Iterate to find it.
+  if (font.GetHeight() > height) {

[msw, 2015/01/13 22:43:59]

Remove this if statement and the return statement it contains, we just want the
loop here. Otherwise, if |font.GetHeight()| > |height|, but |font.GetFontSize()|
< |min_font_size|, this will return the |font| as-is, smaller than the min size.

If we want to avoid running the loop below after running this loop (just for
efficiency's sake, to avoid shrinking here then re-deriving the first larger
size with a height greater than |height|), set a flag, I think like this:

  bool ran_shrink_loop = false;
  while ((font.GetHeight() > height) && 
         (font.GetFontSize() >= min_font_size)) {
    ran_shrink_loop = true;
    ...
  }

  while ((font.GetHeight() <= height && !ran_shrink_loop) ||
         (font.GetFontSize() < min_font_size)) {
    ...
  }

[ananta, 2015/01/13 23:39:40]

I added a new function CreateFontWithHeight which creates a HFONT which matches
the minimum size. That should ensure that we at least have a Font which matches
the criteria. We can leave the if in place now? WDYT?

+    while ((font.GetHeight() > height) &&
+           (font.GetFontSize() >= min_font_size)) {
+      Font derived_font = font.Derive(-1, style);
+      if ((derived_font.GetFontSize() < min_font_size) ||
+          (derived_font.GetFontSize() == font.GetFontSize()))
+        break;
+      DCHECK_LT(derived_font.GetFontSize(), font.GetFontSize());
+      font = derived_font;
+    }
+    return font;
+  }
+
+  while ((font.GetHeight() <= height) ||
+         (font.GetFontSize() < min_font_size)) {

[ananta, 2015/01/13 23:39:40]

I think the CreateFontWithHeight function now alleviates the need to check the
font.GetFontSize() < min_font_size here. 

+    Font derived_font = font.Derive(1, style);
+    if ((derived_font.GetHeight() > height) &&
+        (font.GetFontSize() >= min_font_size))
+      break;
+    DCHECK_GT(derived_font.GetFontSize(), font.GetFontSize());
+    font = derived_font;
+  }
+  return font;
 }
 
 ////////////////////////////////////////////////////////////////////////////////
 // PlatformFontWin, PlatformFont implementation:
 
 Font PlatformFontWin::DeriveFont(int size_delta, int style) const {
   LOGFONT font_info;
   GetObject(GetNativeFont(), sizeof(LOGFONT), &font_info);
   const int requested_font_size = font_ref_->requested_font_size();
   font_info.lfHeight = AdjustFontSize(-requested_font_size, size_delta);
@@ skipping 165 matching lines @@
     style |= Font::ITALIC;
   if (font_metrics.tmUnderlined)
     style |= Font::UNDERLINE;
   if (font_metrics.tmWeight >= kTextMetricWeightBold)
     style |= Font::BOLD;
 
   return new HFontRef(font, font_size, height, baseline, cap_height,
                       ave_char_width, style);
 }
 
-Font PlatformFontWin::DeriveWithCorrectedSize(HFONT base_font) {
-  base::win::ScopedGetDC screen_dc(NULL);
-  gfx::ScopedSetMapMode mode(screen_dc, MM_TEXT);
-
-  base::win::ScopedGDIObject<HFONT> best_font(base_font);
-  TEXTMETRIC best_font_metrics;
-  GetTextMetricsForFont(screen_dc, best_font, &best_font_metrics);
-
-  LOGFONT font_info;
-  GetObject(base_font, sizeof(LOGFONT), &font_info);
-
-  // Set |lfHeight| to negative value to indicate it's the size, not the height.
-  font_info.lfHeight =
-      -(best_font_metrics.tmHeight - best_font_metrics.tmInternalLeading);
-
-  do {
-    // Increment font size. Prefer font with greater size if its height isn't
-    // greater than height of base font.
-    font_info.lfHeight = AdjustFontSize(font_info.lfHeight, 1);
-    base::win::ScopedGDIObject<HFONT> font(CreateFontIndirect(&font_info));
-    TEXTMETRIC font_metrics;
-    GetTextMetricsForFont(screen_dc, font, &font_metrics);
-    if (font_metrics.tmHeight > best_font_metrics.tmHeight)
-      break;
-    best_font.Set(font.release());
-    best_font_metrics = font_metrics;
-  } while (true);
-
-  return Font(new PlatformFontWin(CreateHFontRef(best_font.release())));
-}
-
 // static
 PlatformFontWin::HFontRef* PlatformFontWin::CreateHFontRefFromSkia(
     HFONT gdi_font,
     const TEXTMETRIC& font_metrics) {
   LOGFONT font_info = {0};
   GetObject(gdi_font, sizeof(LOGFONT), &font_info);
 
   // If the font height is passed in as 0, assume the height to be -1 to ensure
   // that we return the metrics for a 1 point font.
   // If the font height is positive it represents the rasterized font's cell
@@ skipping 44 matching lines @@
   SkPaint paint;
   paint.setAntiAlias(!!antialiasing);
   paint.setTypeface(skia_face.get());
   paint.setTextSize(-font_info.lfHeight);
   SkPaint::FontMetrics skia_metrics;
   paint.getFontMetrics(&skia_metrics);
 
   // The calculations below are similar to those in the CreateHFontRef
   // function. The height, baseline and cap height are rounded up to ensure
   // that they match up closely with GDI.
-  const int height = std::ceil(
-      skia_metrics.fDescent - skia_metrics.fAscent + skia_metrics.fLeading);
+  const int height = std::ceil(skia_metrics.fDescent - skia_metrics.fAscent);
   const int baseline = std::max<int>(1, std::ceil(-skia_metrics.fAscent));
   const int cap_height = std::ceil(paint.getTextSize() *
       static_cast<double>(dwrite_font_metrics.capHeight) /
           dwrite_font_metrics.designUnitsPerEm);
 
   // The metrics retrieved from skia don't have the average character width. In
   // any case if we get the average character width from skia then use that or
   // use the text extent technique as documented by microsoft. See
   // GetAverageCharWidthInDialogUnits for details.
   const int ave_char_width =
@@ skipping 87 matching lines @@
   return new PlatformFontWin(native_font);
 }
 
 // static
 PlatformFont* PlatformFont::CreateFromNameAndSize(const std::string& font_name,
                                                   int font_size) {
   return new PlatformFontWin(font_name, font_size);
 }
 
 }  // namespace gfx