Fix gdi32 GetFontData() patching for printing.

On Windows, GetFontData() calls from within sandboxed processes have to
use the font_cache mechanism to work correctly. This requires a
correctly patched GetFontData(), which broke in M76.

https://crbug.com/980577 broke Import Address Table patching for
gdi32.dll. This eventually got fixed, but the final fix in
https://crrev.com/686696 tried to minimize the amount of patching
necessary, and did not get it 100% correct for printing use cases.  As
a result, sometimes utility processes used for printing did not get
patched. This fix by patching utility processes in InitializePDF().
Rearrange the function and update comments along the way.

The font_cache mechanism in the Cloud Print service process also broke
around the same time due to https://crrev.com/660952, but that just got
fixed in https://crrev.com/700317.

Bug: 1005867
Change-Id: I0bb691d8208fbbb9bf885767a959119a388def09
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1826197Reviewed-by: Ken Rockot <rockot@google.com>
Commit-Queue: Lei Zhang <thestig@chromium.org>
Cr-Commit-Position: refs/heads/master@{#700918}

chrome/child/pdf_child_init.cc

@@ -52,39 +52,46 @@ void InitializePDF() {
 #if defined(OS_WIN)
   const base::CommandLine& command_line =
       *base::CommandLine::ForCurrentProcess();
-  std::string process_type =
+  const std::string process_type =
       command_line.GetSwitchValueASCII(switches::kProcessType);
-  bool is_pdf_utility_process = false;
-  if (command_line.HasSwitch(service_manager::switches::kServiceSandboxType)) {
+
+  // Patch utility processes, which includes ones that do PDF to EMF conversion.
+  // They are hard to differentiate because they can also be launched from
+  // chrome/service/ in a different manner vs. from chrome/browser/.
+  bool needs_gdi32_patching = process_type == switches::kUtilityProcess;
+
+  if (!needs_gdi32_patching) {
+    // Windows prior to Win10 use GDI fonts in the PDF PPAPI process.
+    needs_gdi32_patching = process_type == switches::kPpapiPluginProcess &&
+                           base::win::GetVersion() < base::win::Version::WIN10;
+  }
+
+  if (!needs_gdi32_patching) {
+    // Printing uses GDI for fonts on all versions of Windows.
+    // TODO(thestig): Check and see if this is actually necessary.
     std::string service_sandbox_type = command_line.GetSwitchValueASCII(
         service_manager::switches::kServiceSandboxType);
-    if (service_sandbox_type ==
-        service_manager::switches::kPdfCompositorSandbox) {
-      is_pdf_utility_process = true;
-    }
+    needs_gdi32_patching = service_sandbox_type ==
+                           service_manager::switches::kPdfCompositorSandbox;
   }
-  // On Win10, pdf does not use GDI fonts and does not need to run this
-  // initialization for the ppapi process. Printing does still use GDI for
-  // fonts on Win10 though.
-  if (is_pdf_utility_process ||
-      (process_type == switches::kPpapiPluginProcess &&
-       base::win::GetVersion() < base::win::Version::WIN10)) {
-    // Need to patch a few functions for font loading to work correctly. This
-    // can be removed once we switch PDF to use Skia
-    // (https://bugs.chromium.org/p/pdfium/issues/detail?id=11).
+
+  if (!needs_gdi32_patching)
+    return;
+
 #if defined(COMPONENT_BUILD)
-    HMODULE module = ::GetModuleHandleA("pdfium.dll");
-    DCHECK(module);
+  HMODULE module = ::GetModuleHandleA("pdfium.dll");
+  DCHECK(module);
 #else
-    HMODULE module = CURRENT_MODULE();
+  HMODULE module = CURRENT_MODULE();
 #endif  // defined(COMPONENT_BUILD)
 
-    static base::NoDestructor<base::win::IATPatchFunction> patch_get_font_data;
-    patch_get_font_data->PatchFromModule(
-        module, "gdi32.dll", "GetFontData",
-        reinterpret_cast<void*>(GetFontDataPatch));
-    g_original_get_font_data = reinterpret_cast<GetFontDataPtr>(
-        patch_get_font_data->original_function());
-  }
+  // Need to patch GetFontData() for font loading to work correctly. This can be
+  // removed once PDFium switches to use Skia. https://crbug.com/pdfium/11
+  static base::NoDestructor<base::win::IATPatchFunction> patch_get_font_data;
+  patch_get_font_data->PatchFromModule(
+      module, "gdi32.dll", "GetFontData",
+      reinterpret_cast<void*>(GetFontDataPatch));
+  g_original_get_font_data = reinterpret_cast<GetFontDataPtr>(
+      patch_get_font_data->original_function());
 #endif  // defined(OS_WIN)
 }