Add detection of high usage of HFONT in PlatformFontWin

This CL is adding code to detect when GDI Handles (HFONT)
are going to high because too many gfx::Font exists.

There is a plan to fix the incorrect uses of gfx::Font
and these dump will help tracking the source of these leaks.

Bug: 972689
Change-Id: I326938c3751766e01b3c318b5397ef8f4d4f9ae9
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1648398Reviewed-by: Etienne Bergeron <etienneb@chromium.org>
Reviewed-by: Alexei Svitkine <asvitkine@chromium.org>
Reviewed-by: Robert Liao <robliao@chromium.org>
Commit-Queue: Etienne Bergeron <etienneb@chromium.org>
Cr-Commit-Position: refs/heads/master@{#668462}

ui/gfx/platform_font_win.cc

@@ -17,6 +17,7 @@
 
 #include "base/containers/flat_map.h"
 #include "base/debug/alias.h"
+#include "base/debug/dump_without_crashing.h"
 #include "base/feature_list.h"
 #include "base/logging.h"
 #include "base/no_destructor.h"
@@ -44,6 +45,19 @@
 
 namespace {
 
+// Tracking of HFontRef allocations (see: http://crbug/972689). The following
+// code is temporary. It will be used to track and fix incorrect usage of
+// GDI handles.
+
+// Amount of HFontRef objects currently allocated.
+int g_hfontref_total = 0;
+
+// Max amount of HFontRef object before reporting a crash.
+constexpr int kMaxHFontRefObjects = 1024;
+
+// Whether a report already got sent.
+bool g_hfontref_dump_already_sent = false;
+
 // Enable the use of PlatformFontSkia instead of PlatformFontWin.
 const base::Feature kPlatformFontSkiaOnWindows{
     "PlatformFontSkiaOnWindows", base::FEATURE_DISABLED_BY_DEFAULT};
@@ -580,6 +594,18 @@ PlatformFontWin::HFontRef::HFontRef(HFONT hfont,
       requested_font_size_(font_size) {
   DLOG_ASSERT(hfont);
 
+  // We are seeing cases in the field where the amount of HFontRef is above
+  // 10k objects. Each object keeps an HFONT alive, counting towards out 10K GDI
+  // handle limit. This code will help track the source of these issues
+  // (see crbug.com/972689) (todo: etienneb: remove this code when the
+  // experiment is done).
+  ++g_hfontref_total;
+  if (g_hfontref_total > kMaxHFontRefObjects &&
+      !g_hfontref_dump_already_sent) {
+    g_hfontref_dump_already_sent = true;
+    base::debug::DumpWithoutCrashing();
+  }
+
   LOGFONT font_info;
   GetObject(hfont_, sizeof(LOGFONT), &font_info);
   font_name_ = base::UTF16ToUTF8(base::string16(font_info.lfFaceName));
@@ -623,6 +649,7 @@ int PlatformFontWin::HFontRef::GetAverageCharWidthInDialogUnits(
 }
 
 PlatformFontWin::HFontRef::~HFontRef() {
+  --g_hfontref_total;
   DeleteObject(hfont_);
 }