CrOS - Add memory consumption status bar widget behind flag

Pass --memory-widget on CrOS to get a real-time display, updated every 5 seconds, of the system's free memory.  Tooltip and menu itself detail the data from /proc/meminfo.  Also made base::GetSystemMemoryInfo() available on Linux systems to provide detailed data.

BUG=chromium-os:18446
TEST=manual

Review URL: http://codereview.chromium.org/7518010

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@95089 0039d316-1c4b-4281-b951-d872f2087c98

2 files changed, 35 insertions, 10 deletions

diff --git a/base/process_util.h b/base/process_util.h
index 3d9b7d1..5f88c62 100644
--- a/base/process_util.h
+++ b/base/process_util.h
@@ -653,7 +653,14 @@ class BASE_API ProcessMetrics {
   DISALLOW_COPY_AND_ASSIGN(ProcessMetrics);
 };
 
-// Returns the memory commited by the system in KBytes.
+#if defined(OS_LINUX)
+// Retrieves data from /proc/meminfo about system-wide memory consumption.
+// Values are in KB. Returns true on success.
+BASE_API bool GetSystemMemoryInfo(int* total_kb, int* free_kb, int* buffers_kb,
+                                  int* cache_kb, int* shmem_kb);
+#endif
+
+// Returns the memory committed by the system in KBytes.
 // Returns 0 if it can't compute the commit charge.
 BASE_API size_t GetSystemCommitCharge();
 
diff --git a/base/process_util_linux.cc b/base/process_util_linux.cc
index aabd201..3ea383f 100644
--- a/base/process_util_linux.cc
+++ b/base/process_util_linux.cc
@@ -562,7 +562,8 @@ const size_t kMemCacheIndex = 10;
 
 }  // namespace
 
-size_t GetSystemCommitCharge() {
+bool GetSystemMemoryInfo(int* mem_total, int* mem_free, int* mem_buffers,
+                         int* mem_cache, int* shmem) {
   // Synchronously reading files in /proc is safe.
   base::ThreadRestrictions::ScopedAllowIO allow_io;
 
@@ -571,7 +572,7 @@ size_t GetSystemCommitCharge() {
   std::string meminfo_data;
   if (!file_util::ReadFileToString(meminfo_file, &meminfo_data)) {
     LOG(WARNING) << "Failed to open /proc/meminfo.";
-    return 0;
+    return false;
   }
   std::vector<std::string> meminfo_fields;
   SplitStringAlongWhitespace(meminfo_data, &meminfo_fields);
@@ -579,7 +580,7 @@ size_t GetSystemCommitCharge() {
   if (meminfo_fields.size() < kMemCacheIndex) {
     LOG(WARNING) << "Failed to parse /proc/meminfo.  Only found " <<
       meminfo_fields.size() << " fields.";
-    return 0;
+    return false;
   }
 
   DCHECK_EQ(meminfo_fields[kMemTotalIndex-1], "MemTotal:");
@@ -587,13 +588,30 @@ size_t GetSystemCommitCharge() {
   DCHECK_EQ(meminfo_fields[kMemBuffersIndex-1], "Buffers:");
   DCHECK_EQ(meminfo_fields[kMemCacheIndex-1], "Cached:");
 
-  int mem_total, mem_free, mem_buffers, mem_cache;
-  base::StringToInt(meminfo_fields[kMemTotalIndex], &mem_total);
-  base::StringToInt(meminfo_fields[kMemFreeIndex], &mem_free);
-  base::StringToInt(meminfo_fields[kMemBuffersIndex], &mem_buffers);
-  base::StringToInt(meminfo_fields[kMemCacheIndex], &mem_cache);
+  base::StringToInt(meminfo_fields[kMemTotalIndex], mem_total);
+  base::StringToInt(meminfo_fields[kMemFreeIndex], mem_free);
+  base::StringToInt(meminfo_fields[kMemBuffersIndex], mem_buffers);
+  base::StringToInt(meminfo_fields[kMemCacheIndex], mem_cache);
+#if defined(OS_CHROMEOS)
+  // Chrome OS has a tweaked kernel that allows us to query Shmem, which is
+  // usually video memory otherwise invisible to the OS.  Unfortunately, the
+  // meminfo format varies on different hardware so we have to search for the
+  // string.  It always appears after "Cached:".
+  for (size_t i = kMemCacheIndex+2; i < meminfo_fields.size(); i += 3) {
+    if (meminfo_fields[i] == "Shmem:") {
+      base::StringToInt(meminfo_fields[i+1], shmem);
+      break;
+    }
+  }
+#endif
+  return true;
+}
 
-  return mem_total - mem_free - mem_buffers - mem_cache;
+size_t GetSystemCommitCharge() {
+  int total, free, buffers, cache, shmem;
+  if (!GetSystemMemoryInfo(&total, &free, &buffers, &cache, &shmem))
+    return 0;
+  return total - free - buffers - cache;
 }
 
 namespace {