Workaround for Windows-only crash inside delay load helper.

media/base/media_win.cc

Index: media/base/media_win.cc
===================================================================
--- media/base/media_win.cc	(revision 122285)
+++ media/base/media_win.cc	(working copy)
@@ -5,6 +5,7 @@
 #include "media/base/media.h"
 
 #include <windows.h>
+#include <delayimp.h>
 
 #include "base/file_path.h"
 #include "base/logging.h"
@@ -12,6 +13,8 @@
 #include "base/native_library.h"
 #include "base/path_service.h"
 
+#pragma comment(lib, "delayimp.lib")
+
 namespace media {
 
 enum FFmpegDLLKeys {
@@ -21,18 +24,18 @@
 };
 
 // Retrieves the DLLName for the given key.
-static FilePath::CharType* GetDLLName(FFmpegDLLKeys dll_key) {
+static const char* GetDLLName(FFmpegDLLKeys dll_key) {
   // TODO(ajwong): Do we want to lock to a specific ffmpeg version?
   switch (dll_key) {
     case FILE_LIBAVCODEC:
-      return FILE_PATH_LITERAL("avcodec-53.dll");
+      return "avcodec-53.dll";
     case FILE_LIBAVFORMAT:
-      return FILE_PATH_LITERAL("avformat-53.dll");
+      return "avformat-53.dll";
     case FILE_LIBAVUTIL:
-      return FILE_PATH_LITERAL("avutil-51.dll");
+      return "avutil-51.dll";
     default:
       LOG(DFATAL) << "Invalid DLL key requested: " << dll_key;
-      return FILE_PATH_LITERAL("");
+      return "";
   }
 }
 
@@ -44,6 +47,11 @@
   if (g_media_library_is_initialized)
     return true;
 
+  // LoadLibraryEx(..., LOAD_WITH_ALTERED_SEARCH_PATH) cannot handle
+  // relative path.
+  if (!base_path.IsAbsolute())
+    return false;
+
   FFmpegDLLKeys path_keys[] = {
     media::FILE_LIBAVCODEC,
     media::FILE_LIBAVFORMAT,
@@ -52,12 +60,12 @@
   HMODULE libs[arraysize(path_keys)] = {NULL};
 
   for (size_t i = 0; i < arraysize(path_keys); ++i) {
-    FilePath path = base_path.Append(GetDLLName(path_keys[i]));
+    FilePath path = base_path.AppendASCII(GetDLLName(path_keys[i]));
 
     // Use alternate DLL search path so we don't load dependencies from the
     // system path.  Refer to http://crbug.com/35857
     const wchar_t* cpath = path.value().c_str();
-    libs[i] = LoadLibraryEx(cpath, NULL, LOAD_WITH_ALTERED_SEARCH_PATH);
+    libs[i] = ::LoadLibraryEx(cpath, NULL, LOAD_WITH_ALTERED_SEARCH_PATH);
     if (!libs[i])
       break;
   }
@@ -65,17 +73,39 @@
   // Check that we loaded all libraries successfully.  We only need to check the
   // last array element because the loop above will break without initializing
   // it on any prior error.
-  g_media_library_is_initialized = (libs[arraysize(libs) - 1] != NULL);
+  bool media_library_is_initialized = (libs[arraysize(libs) - 1] != NULL);
 
-  if (!g_media_library_is_initialized) {
+  if (!media_library_is_initialized) {
     // Free any loaded libraries if we weren't successful.
     for (size_t i = 0; i < arraysize(libs) && libs[i] != NULL; ++i) {
       FreeLibrary(libs[i]);
       libs[i] = NULL;  // Just to be safe.
     }
+    return false;
   }
 
-  return g_media_library_is_initialized;
+  // Workaround for http://crbug.com/110983

[rvargas (doing something else), 2012/02/27 19:23:40]

nit: There should be a TODO to remove this code when more information is
gathered... this should be an experiment, not a workaround.

+  // LoadLibrary() sometimes AV's when called by delay load helper when we
+  // call function in ffmpeg for the first time, and we don't know why.
+  // Force delay load helper to fix import table here instead.
+  // Theoretically, there is no need to call LoadLibrary() before
+  // __HrLoadAllImportsForDll(), it will call LoadLibrary() itself, but there
+  // is no way to specify LOAD_WITH_ALTERED_SEARCH_PATH when calling
+  // __HrLoadAllImportsForDll(). So we do everything in 2 steps -- first call
+  // LoadLibraryEx(..., LOAD_WITH_ALTERED_SEARCH_PATH), then call
+  // __HrLoadAllImportsForDll(). Overhead is negligible compared to disk
+  // access time.
+  // Note: in case of error we are not unloading DLL because unload requires
+  //       extra resources and should not be necessary; if we ever decide to
+  //       unload by calling __FUnloadDelayLoadedDLL() please add /DELAY:UNLOAD
+  //       to the linker command line.
+  for (size_t i = 0; i < arraysize(path_keys); ++i) {
+    if (FAILED(::__HrLoadAllImportsForDll(GetDLLName(path_keys[i]))))
+      media_library_is_initialized = false;
+  }
+
+  g_media_library_is_initialized = media_library_is_initialized;
+  return media_library_is_initialized;
 }
 
 void InitializeMediaLibraryForTesting() {