Implementation of dwrite font proxy and removal of dwrite font cache

content/common/font_warmup_win.h

Index: content/common/font_warmup_win.h
diff --git a/content/common/font_warmup_win.h b/content/common/font_warmup_win.h
index 7a0e9b502c7e8c4c3d5c36d29532c3305d63cf8f..f41a952a1d2fe770cae6aeded4c8d69d0381d5ca 100644
--- a/content/common/font_warmup_win.h
+++ b/content/common/font_warmup_win.h
@@ -13,14 +13,6 @@ class SkTypeface;
 
 namespace content {
 
-// Make necessary calls to cache the data for a given font, used before
-// sandbox lockdown.
-CONTENT_EXPORT void DoPreSandboxWarmupForTypeface(SkTypeface* typeface);
-
-// Get the shared font manager used during pre-sandbox warmup for DirectWrite
-// fonts.
-CONTENT_EXPORT SkFontMgr* GetPreSandboxWarmupFontMgr();
-
 class GdiFontPatchData {
  public:
   virtual ~GdiFontPatchData() {}
@@ -43,13 +35,23 @@ CONTENT_EXPORT size_t GetEmulatedGdiHandleCountForTesting();
 // Testing method to reset the table of emulated GDI handles.
 CONTENT_EXPORT void ResetEmulatedGdiHandlesForTesting();
 
-// Sets the pre-sandbox warmup font manager directly. This should only be used
-// for testing the implementation.
-CONTENT_EXPORT void SetPreSandboxWarmupFontMgrForTesting(SkFontMgr* fontmgr);
-
-// Warmup the direct write font manager for content processes.
-CONTENT_EXPORT void WarmupDirectWrite();
-
+// Directwrite connects to the font cache service to retrieve information about
+// fonts installed on the system etc. This works well outside the sandbox and
+// within the sandbox as long as the lpc connection maintained by the current
+// process with the font cache service remains valid. It appears that there
+// are cases when this connection is dropped after which directwrite is unable
+// to connect to the font cache service which causes problems with characters
+// disappearing.
+// Directwrite has fallback code to enumerate fonts if it is unable to connect
+// to the font cache service. We need to intercept the following APIs to
+// ensure that it does not connect to the font cache service.
+// NtALpcConnectPort
+// OpenSCManagerW
+// OpenServiceW
+// StartServiceW
+// CloseServiceHandle.
+// These are all IAT patched.
+CONTENT_EXPORT void PatchServiceManagerCalls();
 }  // namespace content
 
 #endif  // CONTENT_COMMON_FONT_WARMUP_WIN_H_