Revert "[logging] Use OFStream for log events"

This reverts commit 06ff9e97.

Reason for revert: Breaks deopt information with --prof. Deopts no longer show up properly in the logfile / profview

Original change's description:
> [logging] Use OFStream for log events
> 
> This simplifies a few operations and removes the size limitations
> implied by the message buffer used.
> 
> Change-Id: I8b873a0ffa399a037ff5c2501ba4b68158810968
> Reviewed-on: https://chromium-review.googlesource.com/724285
> Commit-Queue: Camillo Bruni <cbruni@chromium.org>
> Reviewed-by: Adam Klein <adamk@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#48766}

TBR=adamk@chromium.org,cbruni@chromium.org

Change-Id: I290da0b2472ad0e765b765b26bdde334253376e3
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://chromium-review.googlesource.com/730164Reviewed-by: Benedikt Meurer <bmeurer@chromium.org>
Commit-Queue: Benedikt Meurer <bmeurer@chromium.org>
Cr-Commit-Position: refs/heads/master@{#48776}

src/log-utils.h

@@ -13,7 +13,6 @@
 #include "src/base/compiler-specific.h"
 #include "src/base/platform/mutex.h"
 #include "src/flags.h"
-#include "src/ostreams.h"
 
 namespace v8 {
 namespace internal {
@@ -23,7 +22,8 @@ class Logger;
 // Functions and data for performing output of log messages.
 class Log {
  public:
-  Log(Logger* log, const char* log_file_name);
+  // Performs process-wide initialization.
+  void Initialize(const char* log_file_name);
 
   // Disables logging, but preserves acquired resources.
   void stop() { is_stopped_ = true; }
@@ -66,9 +66,11 @@ class Log {
     // Append string data to the log message.
     void PRINTF_FORMAT(2, 0) AppendVA(const char* format, va_list args);
 
+    // Append a character to the log message.
+    void Append(const char c);
+
     // Append double quoted string to the log message.
     void AppendDoubleQuotedString(const char* string);
-    void AppendDoubleQuotedString(String* string);
 
     // Append a heap string.
     void Append(String* str);
@@ -86,32 +88,37 @@ class Log {
     // Helpers for appending char, C-string and heap string without
     // buffering. This is useful for entries that can exceed the 2kB
     // limit.
-    void AppendEscapedString(String* source);
-    void AppendEscapedString(String* source, int len);
-
-    // Delegate insertion to the underlying {log_}.
-    template <typename T>
-    MessageBuilder& operator<<(T value) {
-      log_->os_ << value;
-      return *this;
-    }
+    void AppendUnbufferedChar(char c);
+    void AppendUnbufferedCString(const char* str);
+    void AppendUnbufferedHeapString(String* source);
 
-    // Finish the current log line an flush the it to the log file.
+    // Write the log message to the log file currently opened.
     void WriteToLogFile();
 
    private:
     Log* log_;
     base::LockGuard<base::Mutex> lock_guard_;
+    int pos_;
   };
 
  private:
-  static FILE* CreateOutputHandle(const char* file_name);
+  explicit Log(Logger* logger);
+
+  // Opens stdout for logging.
+  void OpenStdout();
+
+  // Opens file for logging.
+  void OpenFile(const char* name);
+
+  // Opens a temporary file for logging.
+  void OpenTemporaryFile();
 
   // Implementation of writing to a log file.
   int WriteToFile(const char* msg, int length) {
     DCHECK_NOT_NULL(output_handle_);
-    os_.write(msg, length);
-    DCHECK(!os_.bad());
+    size_t rv = fwrite(msg, 1, length, output_handle_);
+    DCHECK_EQ(length, rv);
+    USE(rv);
     return length;
   }
 
@@ -121,7 +128,6 @@ class Log {
   // When logging is active output_handle_ is used to store a pointer to log
   // destination.  mutex_ should be acquired before using output_handle_.
   FILE* output_handle_;
-  OFStream os_;
 
   // mutex_ is a Mutex used for enforcing exclusive
   // access to the formatting buffer and the log file or log memory buffer.
@@ -129,7 +135,7 @@ class Log {
 
   // Buffer used for formatting log messages. This is a singleton buffer and
   // mutex_ should be acquired before using it.
-  char* format_buffer_;
+  char* message_buffer_;
 
   Logger* logger_;