Allow to retrieve id of a module from memory instead of going to disk for iOS.

Allow macho_id and macho_walker to read data from memory.
 Wire up this when reading module on iOS.
Review URL: http://breakpad.appspot.com/319001

git-svn-id: http://google-breakpad.googlecode.com/svn/trunk@873 4c0a9323-5329-0410-9bdc-e9ce6186880e

src/common/mac/macho_walker.h

@@ -52,7 +52,8 @@ class MachoWalker {
                                       off_t offset, bool swap, void *context);
 
   MachoWalker(const char *path, LoadCommandCallback callback, void *context);
-  MachoWalker(int file_descriptor, LoadCommandCallback callback, void *context);
+  MachoWalker(void *memory, size_t size, LoadCommandCallback callback,
+              void *context);
   ~MachoWalker();
 
   // Begin walking the header for |cpu_type|.  If |cpu_type| is 0, then the
@@ -68,7 +69,7 @@ class MachoWalker {
 
   // Read |size| bytes from the opened file at |offset| into |buffer|
   bool ReadBytes(void *buffer, size_t size, off_t offset);
-  
+
   // Return the current header and header offset
   bool CurrentHeader(struct mach_header_64 *header, off_t *offset);
 
@@ -87,19 +88,25 @@ class MachoWalker {
   // File descriptor to the opened file
   int file_;
 
+  // Memory location to read from.
+  void *memory_;
+
+  // Size of the memory segment we can read from.
+  size_t memory_size_;
+
   // User specified callback & context
   LoadCommandCallback callback_;
   void *callback_context_;
-  
+
   // Current header, size, and offset.  The mach_header_64 is used for both
   // 32-bit and 64-bit headers because they only differ in their last field
-  // (reserved).  By adding the |current_header_size_| and the 
+  // (reserved).  By adding the |current_header_size_| and the
   // |current_header_offset_|, you can determine the offset in the file just
   // after the header.
   struct mach_header_64 *current_header_;
   unsigned long current_header_size_;
   off_t current_header_offset_;
-  
+
  private:
   MachoWalker(const MachoWalker &);
   MachoWalker &operator=(const MachoWalker &);