Adding blink gc memory dump infrastructure for thread specific dumps.

Source/platform/heap/BlinkGCMemoryDumpProvider.cpp

Index: Source/platform/heap/BlinkGCMemoryDumpProvider.cpp
diff --git a/Source/platform/heap/BlinkGCMemoryDumpProvider.cpp b/Source/platform/heap/BlinkGCMemoryDumpProvider.cpp
index 7db5047e1e7f5b82101318b4ab4bb99047ba2e7c..e3db8dbe9181c954453ea13c5d5ad2f8431c300f 100644
--- a/Source/platform/heap/BlinkGCMemoryDumpProvider.cpp
+++ b/Source/platform/heap/BlinkGCMemoryDumpProvider.cpp
@@ -18,12 +18,22 @@ BlinkGCMemoryDumpProvider* BlinkGCMemoryDumpProvider::instance()
     return &instance;
 }
 
-bool BlinkGCMemoryDumpProvider::onMemoryDump(blink::WebProcessMemoryDump* memoryDump)
+BlinkGCMemoryDumpProvider::~BlinkGCMemoryDumpProvider()
 {
+}
+
+bool BlinkGCMemoryDumpProvider::onMemoryDump(WebProcessMemoryDump* memoryDump)
+{
+    // The current heap statistics are added to the memory dump.
     WebMemoryAllocatorDump* allocatorDump = memoryDump->createMemoryAllocatorDump("blink_gc");
     allocatorDump->AddScalar("inner_size", "bytes", Heap::allocatedObjectSize());
     allocatorDump->AddScalar("outer_size", "bytes", Heap::allocatedSpace());
     allocatorDump->AddScalar("estimated_live_object_size", "bytes", Heap::estimatedLiveObjectSize());
+
+    // If available, the last GC memory statistics are added.
+    if (Heap::getLastProcessMemoryDump())
+        memoryDump->takeAllDumpsFrom(Heap::getLastProcessMemoryDump());

[Primiano Tucci (use gerrit), 2015/05/22 15:50:21]

Ok here you need the TODO pointing to crbug.com/490783 and you should have an
"else: return false" once 490783 gets fixed.

[ssid, 2015/05/22 16:05:16]

But we are dumping some overall numbers even if the last gc dump isn't
available. Also, there can be cases where we are dumping empty dumps, which
can't be detected here. ie, no GC happened in between and we still swap the
empty object.

+
     return true;
 }
 
@@ -31,8 +41,4 @@ BlinkGCMemoryDumpProvider::BlinkGCMemoryDumpProvider()
 {
 }
 
-BlinkGCMemoryDumpProvider::~BlinkGCMemoryDumpProvider()

[Primiano Tucci (use gerrit), 2015/05/22 15:50:21]

Is this intended? I think you accidentally removed the dtor (it's still there in
the header)

[ssid, 2015/05/22 16:05:16]

It is moved up to maintain the function order in header.

-{
-}
-
 } // namespace blink